tag:theconversation.com,2011:/africa/topics/flies-2141/articlesFlies – The Conversation2024-03-05T13:59:52Ztag:theconversation.com,2011:article/2132002024-03-05T13:59:52Z2024-03-05T13:59:52ZRobber flies track their beetle prey using tiny microbursts of movement<figure><img src="https://images.theconversation.com/files/553851/original/file-20231015-26-ku2y0f.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Robber flies visually track their prey before spearing it with their proboscis.</span> <span class="attribution"><span class="source">Paloma Gonzalez-Bellido</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>April in the Florida Panhandle. It was hot, humid, and a thunderstorm was lurking. But as a fresh graduate student, I was relieved for the escape from my first brutal Minnesota winter. I was accompanying my adviser, <a href="https://scholar.google.com/citations?user=OpaFwzoAAAAJ&hl=en&oi=ao">Paloma Gonzalez-Bellido</a>, on a project that would end up dominating <a href="https://scholar.google.com/citations?user=oux0RxAAAAAJ&hl=en">my Ph.D. work</a>. Out in the scrubland, my eyes darted at every movement, on the alert for an insect that likes shiny beads. </p>
<p><a href="https://doi.org/10.1093/aesa/43.2.227"><em>Laphria saffrana</em></a>, also known as robber flies, are chunky black and yellow flies. Most of a laphria’s head is made up of its large eyes, between which sits a formidable proboscis – a long, tubular mouthpart that can deliver a potent venom capable of incapacitating prey in a heartbeat.</p>
<p>The photos Paloma showed me before we got there, though stunning, were of no help in looking for the fly. There were insects flying in every direction, their movements a blur, making it impossible to pick out any details. I only had a split second to figure out whether the thing I was seeing was a laphria, a similarly colored yellowjacket wasp, or something else entirely. </p>
<p>Despite their <a href="https://doi.org/10.1016/j.cub.2017.02.032">relatively crude vision</a>, the flies I was looking for are far more adept than I am at picking out the insects they’re targeting. Somehow they’re able to zero in on their prey of choice: beetles. Based on her field observations the previous year, Paloma thought they did this by looking for the flash of beetle wings.</p>
<p>If she was right, laphria have hit upon an ingenious trick that balances the need for speed, accuracy and specificity. Here are some of the clues we’ve found to <a href="https://doi.org/10.1016/j.cub.2023.06.019">the secrets of their success</a>. </p>
<h2>Following the flash</h2>
<p>Paloma had previously studied other predator insects such as dragonflies and killer flies. Their <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/compound-eye">compound eyes</a> don’t provide a lot of detail about the visual world, making it possible to trick them into chasing simple beads as if they were their prey insects.</p>
<p>But when Paloma tried the same sleight of hand on laphria, they wouldn’t go for the regular black beads. They chased only clear beads. </p>
<p>The one important difference between laphria and the other predators Paloma had studied is that they’re picky eaters. Their prey of choice are beetles. So, Paloma and our collaborator, Jennifer Talley, speculated that the reason laphria are attracted to shiny beads is because they reflected light and flashed like the clear wings of a beetle.</p>
<p>In Florida, we tested this idea by swapping out the plain black beads for a panel of LED lights that we could program to flash in sequence at a frequency that matched the wing beats of beetles, which can be anywhere from 80 to 120 beats per second. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/m5gQ1Bhmag4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The experimental setup, with a robber fly sitting on a log facing the LED light panel.</span></figcaption>
</figure>
<p>In an outdoor enclosure, Paloma placed previously caught robber flies one after the other on a log. Outside, Jennifer and I controlled the LED panel in front of the log and the high-speed cameras that captured the action.</p>
<p>The LED pixels flashed in sequence, simulating a moving target. Laphria tracked the lights with keen interest only when they flashed at the same frequency at which beetles flapped their wings.</p>
<p>But even as our initial experiments began confirming the hypothesis, a new puzzle presented itself. How do the flies accurately track their prey?</p>
<h2>Unique strategy to track and identify</h2>
<p>Before they give chase, all visual predators, including laphria, need to accurately track their prey’s movements. Although many animals have this ability, what we found in laphria was, to our surprise, a slightly tweaked formula compared with other predators. Their strategy allows them not only to accurately track but also count those flashes from their prey’s wing movements.</p>
<p>When I looked at the high-speed videos of laphria tracking the flashing LEDs and actual beetles, I noticed that they primarily moved their head in short bursts, called <a href="https://eyewiki.aao.org/Saccade">saccades</a>, interspersed with little or no other movements. These saccades are extremely quick, lasting less than 40 milliseconds, and the time between them is only slightly longer. To the naked eye, this looks like continuous motion, but our high-speed videos show otherwise. The degree to which the flies moved their heads during each burst depended on the speed of the target and how far off center it was from the direction of the fly’s gaze.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ZnuEHGsGz9k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Watch a robber fly watching moving lights it perceives as a prey beetle.</span></figcaption>
</figure>
<p><a href="https://doi.org/10.1016/j.cub.2023.06.019">What our findings told us</a> is that instead of continuously moving their heads to maintain the position of the target within the most sensitive parts of their eyes, laphria allow it to pass over their retina, moving only when it slips out of focus. We think this strategy helps them count the flashes of the prey’s beating wings, which determines their continued interest.</p>
<p>That is, the laphria know the wingbeat frequency of their most tasty prey and so pay attention to flashes that match. If the flash count matches their expectations, they will continue to track the target after it slips out of the sensitive zone of their eyes.</p>
<p>To bring it back into focus, though, they have to account for its speed and the position where they last saw it. Because the size of the saccade matches the speed of the prey, we think the laphria are keeping track of how fast the prey moves while at the same time counting the flashes from its wingbeats. So once a beetle slips out of focus, the predator knows how much to move its head to refocus.</p>
<p>Even though people track moving objects all the time – like while playing sports such as baseball or tennis or even just while watching a bird fly by – <a href="https://www.freethink.com/series/the-edge/eye-tracking">it’s a complex process</a>. It involves dynamic cross-talk between the visual and muscular systems.</p>
<p>Regardless of the motivation, the goal while visually tracking a target is the same – to train the most sensitive zone of the eyes, <a href="https://www.ncbi.nlm.nih.gov/books/NBK554706/">known as the fovea</a>, onto the item of interest. <em>Laphria saffrana</em> have seemingly tweaked that rule so they can learn more about the target. Their customized prediction strategy allows them to accurately locate and quickly chase down their very specific dietary needs.</p><img src="https://counter.theconversation.com/content/213200/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Siddhant Pusdekar does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Not much is known about the predator fly Laphria saffrana. New research identified how they count the wingbeats of their favored prey, letting it slip out of focus before adjusting their heads.Siddhant Pusdekar, Graduate Researcher in Ecology, Evolution and Behavior, University of MinnesotaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2153352023-10-16T02:49:22Z2023-10-16T02:49:22ZFly season: what to know about Australia’s most common flies and how to keep them away<figure><img src="https://images.theconversation.com/files/553893/original/file-20231016-29-hgfpk6.jpg?ixlib=rb-1.1.0&rect=7%2C22%2C4987%2C3302&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-housefly-musca-domestica-2264882059">Shutterstock</a></span></figcaption></figure><p>As the days grow longer and temperatures climb, we’re greeted by a familiar chorus of buzzing. It’s fly season again. </p>
<p>This year is off to a bumper start, with <a href="https://www.9news.com.au/national/flies-sydney-influx-insects/ecb6696a-2aea-4da9-bc32-5f194ce2ea00">bush flies swarming beach-goers</a>, <a href="https://www.ashburton.wa.gov.au/news/residents-alerted-to-increased-march-fly-activity/1542">March flies on the march</a>, and <a href="https://www.portnews.com.au/story/8045459/virus-warning-as-mosquito-numbers-explode/">mosquitoes taking to the skies</a> en masse.</p>
<p>But with almost a million species worldwide and some 30,000 calling Australia home, the (<a href="https://media.bom.gov.au/releases/1177/warmer-and-drier-spring-forecast-after-warmest-winter-on-record/">unusually</a>) warm weather also presents an opportunity to appreciate these remarkable and essential insects with whom we share our world.</p>
<p>Despite their sheer diversity, we’re likely to encounter only a select few flies daily. So who are these curious insects, and how should we think about their presence in our lives?</p>
<h2>Familiar faces</h2>
<p><a href="https://en.wikipedia.org/wiki/Musca_vetustissima">Bush flies</a> (<em>Musca vetustissima</em>) are the iconic Australian fly, and are found country-wide. They slake their thirst on the sweat and tears of mammals and so linger around our heads, shoulders and faces in search of a refreshing drink. </p>
<p>They’re so persistent that they’re credited with inspiring the “<a href="https://en.wikipedia.org/wiki/Aussie_salute">Aussie salute</a>”. These small explorers are otherwise harmless, and pose no serious threat to health or home beyond being a mild nuisance. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/553878/original/file-20231015-19-1l4j90.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of a man in an Australian flag hat waving his hand in front of his face." src="https://images.theconversation.com/files/553878/original/file-20231015-19-1l4j90.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553878/original/file-20231015-19-1l4j90.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553878/original/file-20231015-19-1l4j90.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553878/original/file-20231015-19-1l4j90.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553878/original/file-20231015-19-1l4j90.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553878/original/file-20231015-19-1l4j90.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553878/original/file-20231015-19-1l4j90.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The ‘Aussie salute’ is a characteristic gesture of waving flies – specifically the persistent Australian bush flies – away from the face.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Aussie_salute#/media/File:Aussie_salute.jpg">Mick and Rortles / Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Similar in appearance are <a href="https://en.wikipedia.org/wiki/Housefly">house flies</a> (<em>Musca domestica</em>), which frequent our homes. Unlike bush flies, however, they’re more interested in scraps of food and waste left unprotected. They regurgitate digestive juices to break solids into a mush more amenable to their straw-like mouths, and can pose a minor hygiene concern as a consequence.</p>
<p><a href="https://en.wikipedia.org/wiki/Calliphoridae">Blowflies</a> bring some sparkle to the fly world, and are easily recognised by their often large, shiny bodies. Although sometimes a pest, they’re also voracious scavengers and effective pollinators. In this way they do their bit to break down organic matter, recycle nutrients, and transport pollen to support plant life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/553895/original/file-20231016-21-m2xrcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of a sparkly, metallic blue fly perched on a green leaf or stem." src="https://images.theconversation.com/files/553895/original/file-20231016-21-m2xrcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553895/original/file-20231016-21-m2xrcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553895/original/file-20231016-21-m2xrcy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553895/original/file-20231016-21-m2xrcy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553895/original/file-20231016-21-m2xrcy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553895/original/file-20231016-21-m2xrcy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553895/original/file-20231016-21-m2xrcy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The golden bluebottle (Chrysomya incisuralis) is one of many species of Australian blowfly.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/australian-golden-bluebottle-blowfly-known-chrysomya-1676775739">Shutterstock</a></span>
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<p>The sheer size of <a href="https://en.wikipedia.org/wiki/Tabanidae">horseflies</a> makes them powerful fliers, which can often be heard and seen at a distance. Females demand a blood meal and so pack a hearty bite to mammals, including us, and can be a nuisance to livestock. They are also, however, excellent pollinators, with <a href="https://doi.org/10.1016/j.sajb.2009.06.015">some orchids</a> relying on their hard work and specialised mouthparts for survival.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/does-zika-virus-pose-a-threat-to-australia-53557">Does Zika virus pose a threat to Australia?</a>
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</em>
</p>
<hr>
<p>Finally, and famously, are <a href="https://en.wikipedia.org/wiki/Mosquito">mosquitoes</a>. (Yes, they are a type of fly.) Many summer evenings are spent swatting females as they sip our blood. </p>
<p>More serious is their role as vectors for diseases that have <a href="https://doi.org/10.1641/B580812">helped to topple empires</a>, and which remain a significant health burden, especially in the Global South. <a href="https://doi.org/10.1016/S0140-6736(12)60034-8">Malaria</a> is among the farthest-reaching, while <a href="https://www.cdc.gov/ross-river-virus/healthcareproviders/">Ross River Virus</a>, <a href="http://www.cdc.gov/chikungunya/">chikungunya</a>, <a href="https://theconversation.com/does-zika-virus-pose-a-threat-to-australia-53557">zika</a> and <a href="http://www.cdc.gov/dengue/">dengue</a> all circulate with help from mosquitoes.</p>
<h2>Shoo fly?</h2>
<p>For the minority of flies that prove a recurring annoyance, the primary goal is to deter rather than kill them. In this case, the remedies are simple:</p>
<ul>
<li>use topical repellents containing DEET or Picaridin, and wear loose-fitting clothing when outside</li>
<li>install flyscreens in the house, and check them regularly for holes</li>
<li>keep your food covered, both at home and when out enjoying the warm weather</li>
<li>empty your bins regularly and minimise standing water, both of which can attract unwanted attention.</li>
</ul>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/the-battle-against-bugs-its-time-to-end-chemical-warfare-111629">The battle against bugs: it's time to end chemical warfare</a>
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<p>Avoid <a href="https://theconversation.com/the-battle-against-bugs-its-time-to-end-chemical-warfare-111629">reaching for the bug-bombs and sprays</a>, which have devastating impacts on beneficial insects. If a chemical last resort is required, choose selective sprays rather than broad-spectrum options such as pyrethroids and neonicotinoids, which kill the many good bugs with the few bad ones. </p>
<p>Similarly, those noise-emitting, electrified or smelly gadgets that promise a fly-free existence are best avoided, as most are either <a href="https://theconversation.com/the-buzz-from-your-smartphone-wont-stop-mosquito-bites-92611">ineffective</a>, or harm far more than their intended targets.</p>
<h2>From pesky to paramount</h2>
<p>While our daily encounters with a handful of fly species may taint our perception of the group as a whole, such a view is both unwarranted and unjustified. Flies are among the most diverse animals on the planet, and are utterly crucial for the healthy function of our ecosystems.</p>
<p>Many, like <a href="https://en.wikipedia.org/wiki/Hover_fly">hover flies</a>, are important pollinators. In an era of pollinator declines and <a href="https://www.fao.org/documents/card/en/c/cc3017en">heightened food insecurity</a>, their ongoing work is <a href="https://doi.org/10.1080/14888386.2008.9712892">key to supporting agricultural production</a>, and plant life more generally. </p>
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<img alt="A photo of a skinny black fly sitting in the middle of a yellow and pink flower." src="https://images.theconversation.com/files/553897/original/file-20231016-23-cxxzcl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/553897/original/file-20231016-23-cxxzcl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/553897/original/file-20231016-23-cxxzcl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/553897/original/file-20231016-23-cxxzcl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/553897/original/file-20231016-23-cxxzcl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=519&fit=crop&dpr=1 754w, https://images.theconversation.com/files/553897/original/file-20231016-23-cxxzcl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=519&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/553897/original/file-20231016-23-cxxzcl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=519&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The larvae of the black soldier fly (Hermetia illucens) are highly effective decomposers, eating twice their own bodyweight every day.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Hermetia_illucens#/media/File:Hermetia_illucens_MHNT_Fronton.jpg">Didier Descouens / Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>On the other side of the circle of life are outstanding decomposers, such as <a href="https://en.wikipedia.org/wiki/Hermetia_illucens">black soldier flies</a>. Each individual larva can eat twice its bodyweight daily, which at the scale of tens of thousands of grubs presents a promising pathway towards sustainable waste management. They are also a rich source of protein for livestock, <a href="https://theconversation.com/food-for-thought-feeding-our-growing-population-with-flies-64374">or even humans</a>.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/food-for-thought-feeding-our-growing-population-with-flies-64374">Food for thought: feeding our growing population with flies</a>
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</em>
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<p>Just as a very few flies are pests, many serve as remedies in their role as biological controls. The 10,000-odd species of <a href="https://en.wikipedia.org/wiki/Tachinidae">tachinid</a>, or example, make a living as parasitoids of other insects. That is, they lay their eggs inside, and eventually kill, the developing young of others, which include pest caterpillars, flies and bugs.</p>
<p>Moreover, flies have proven invaluable in <a href="https://theconversation.com/trust-me-im-an-expert-forensic-entomology-or-what-bugs-can-tell-police-about-when-someone-died-124416">forensics</a>, <a href="https://doi.org/10.1038/35042080">medicine and scientific research</a>, and <a href="https://doi.org/10.3389/fenvs.2023.1146052">environmental monitoring</a>, underscoring how deeply our lives intertwine with theirs. </p>
<h2>Fly on</h2>
<p>As the warm weather rolls around, then, take the opportunity to look a little closer at our nimble neighbours, and consider both their <a href="https://dx.doi.org/10.1111/j.1469-185X.2007.00018.x">staggering diversity</a> and the vital roles they humbly fill. The natural world – us included – would not be the same without them.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/trust-me-im-an-expert-forensic-entomology-or-what-bugs-can-tell-police-about-when-someone-died-124416">Trust Me, I'm An Expert: forensic entomology, or what bugs can tell police about when someone died</a>
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<img src="https://counter.theconversation.com/content/215335/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas White receives funding from The Australian Research Council, Agrifutures, and the Hermon Slade Foundation. He is also affiliated with the conservation charity Invertebrates Australia. </span></em></p><p class="fine-print"><em><span>Tanya Latty receives funding from the Australian Research Council and AgriFutures Australia. She is affiliated with conservation organisation Invertebrates Australia and is president of the Australasian Society for the Study of Animal Behaviour. </span></em></p>Early warm weather has triggered a bumper season for Australia’s 30,000 fly species.Thomas White, Senior lecturer, University of SydneyTanya Latty, Associate professor, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2038312023-09-04T12:16:58Z2023-09-04T12:16:58ZHow do flies find every stinky garbage dumpster? A biologist explains their sensory superpower<figure><img src="https://images.theconversation.com/files/538392/original/file-20230719-17-hhlu4f.jpg?ixlib=rb-1.1.0&rect=70%2C60%2C6619%2C4406&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The blow fly's antenna is a specialized organ that helps the fly detect food quicker than its competitors. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/gold-fly-on-food-royalty-free-image/1170893429?adppopup=true">heckepics/iStock via Getty Images </a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<blockquote>
<p><strong>How do the green-and-blue flies find stinky garbage dumpsters during the summer heat? Joey, 10, Wausau, Wisconsin</strong></p>
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<p>How is it that a fly always seems to be buzzing around your food moments after you sit down for an outdoor meal?</p>
<p>The answer is practice. Or, more specifically: evolution. Flies and other insects have been on a multimillion-year journey of evolution, honing their ability to detect food. Being able to zero in on nutritious meals is a matter of life and death. </p>
<p>The family of flies <a href="https://science.iupui.edu/biology/research/faculty-labs/picard-lab/index.html">that I study</a> – the blow flies – are the buzzing ones that are usually a beautiful metallic blue, with bronze and green colors. They’ve perfected their ability to quickly sense the smells that naturally come off picnics and trash cans because they are a source of food for their offspring, also known as <a href="https://www.britannica.com/science/maggot-insect-larva">maggots</a>. </p>
<p>There is a lot of competition for a resource like an overflowing dumpster because of how nutritious garbage, and the meat that is rotting in it, is. But the blow flies can sense these odors long before their competitors or people can, and tend to <a href="https://www.theguardian.com/science/2010/sep/23/flies-murder-natural-history-museum">show up to the scene first</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/538065/original/file-20230718-27-j1dmtd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Fly eats meat." src="https://images.theconversation.com/files/538065/original/file-20230718-27-j1dmtd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/538065/original/file-20230718-27-j1dmtd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/538065/original/file-20230718-27-j1dmtd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/538065/original/file-20230718-27-j1dmtd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/538065/original/file-20230718-27-j1dmtd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/538065/original/file-20230718-27-j1dmtd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/538065/original/file-20230718-27-j1dmtd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Flies’ antennae help them track down food from far distances.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/adult-greenbottle-fly-royalty-free-image/1406254324?phrase=flies%2Beating%2Bmeat">ViniSouza128/iStock via Getty Images</a></span>
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<h2>How do flies know where to go?</h2>
<p>Sensing systems differ depending on the insect and species. The blow flies’ main sensing organ is their <a href="https://en.wikipedia.org/wiki/Antenna_(biology)">antennae</a>, two thin projections from the head that are covered in tiny hairs. These fine hairs are made up of special cells that contain <a href="https://doi.org/10.1007/s00253-011-3417-x">receptors for specific odors</a>. </p>
<p>Think about a batch of chocolate chip cookies fresh from the oven. You can detect their delicious scent because we humans have receptors on the surfaces of the cells that line the inside of our noses. These receptors send signals to the brain: yummy food ahead. They’re detecting the sweet smell of sugar-based molecules, an energy-rich food source for us. </p>
<p>What’s a “good” or a “bad” odor can differ depending on the animal doing the smelling. The enticing rotting meat stench that a fly finds delightful is perceived quite differently by a person passing by a stinking dumpster on a hot day.</p>
<p>But any fly that can detect the useful odor signal, which means “nutritious fly food here,” will have an advantage. Over time, the insects that have the receptors for those scents will have better survival rates and produce more offspring.</p>
<p>Not all smells are good, though, and being able to smell something bad can also protect whoever is sniffing it – whether that’s you or an insect. Think of the skunk spray warning smell. It won’t necessarily harm you, but it lets you know to avoid its source. </p>
<figure class="align-center ">
<img alt="A fly has detected a piece of dessert." src="https://images.theconversation.com/files/533741/original/file-20230623-23-6np9vj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533741/original/file-20230623-23-6np9vj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=381&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533741/original/file-20230623-23-6np9vj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=381&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533741/original/file-20230623-23-6np9vj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=381&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533741/original/file-20230623-23-6np9vj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=479&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533741/original/file-20230623-23-6np9vj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=479&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533741/original/file-20230623-23-6np9vj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=479&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Flies can sense odors long before humans and their competitors can.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/spoiled-dessert-royalty-free-image/1125293670?phrase=fly+insect+food&adppopup=true">Boris SV/Moment via Getty Images</a></span>
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<h2>Providing for offspring</h2>
<p>For more than 15 years, I’ve traveled to different parts of the world, where I expose rotten meat and <a href="https://science.iupui.edu/biology/research/faculty-labs/picard-lab/index.html">wait for flies to appear</a>. My research is related to understanding how an environment influences a fly’s ability to search for and find its food source, its sole purpose of living. For example, flies rely on wind to carry scents across varying environments. </p>
<p>Warmer temperatures promote fly activity because they’re <a href="https://en.wikipedia.org/wiki/Poikilotherm">poikilothermic</a> – meaning cold-blooded – and need heat to warm up their muscles for flight. <a href="https://theconversation.com/flies-evade-your-swatting-thanks-to-sophisticated-vision-and-neural-shortcuts-187051">Flies use visual cues</a> to fly through the air and to avoid obstacles, so they’re more active during the daytime.</p>
<p>Blow flies can <a href="https://doi.org/10.1146/annurev.en.10.010165.000403">travel up to 28 miles for food</a>. Most of the time when I expose a stinky rotten meat bait, a large group of flies <a href="https://www.youtube.com/shorts/FZnHA4U0NJM">will come right away</a>. But other times I’m surprised when no flies come to enjoy the gross buffet I’ve prepared.</p>
<p>When a female fly smells something that might be a good food source for her babies, she lands on it and assesses whether there’s enough to support her 400 or so eggs. A mom fly’s ability to smell out a good nursery for her offspring is the key to the survival of the species and ultimately why this sense is so strong. </p>
<p>Male flies are less interested in these smells as a sign of food. But since they can signal where to find female flies for mating, males will still respond to the scent of a steaming dumpster.</p>
<p>Flies have evolved to be superior garbage-smellers because this superpower helps them survive. The reason they manage to find dumpsters wherever they exist is the same reason they’ll show up to your picnic to check what’s on the menu – they’re sniffing for sustenance that will help them create the next generation of flies. </p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/203831/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christine Picard receives funding from the National Science Foundation, the National Geographic Society, the National Institute of Justice, and the US Department of Defense. </span></em></p>Flies often beat out competitors for food because of their specialized sensing organs called antennae.Christine Picard, Associate Professor of Biology, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2086392023-07-04T15:11:39Z2023-07-04T15:11:39ZBiting flies are attracted to blue traps – we used AI to work out why<p>Flies which feast on blood – such as tsetse and horse flies – inflict painful bites and spread debilitating diseases among people and animals alike. So a lot of work has gone into designing the most efficient traps to control the populations of these flies.</p>
<p>Biting fly traps tend to be blue, because decades of field research has shown that such flies find this colour especially attractive. But it’s never been clear why these flies find blue to be so irresistible – especially since blue objects are not a common sight in the natural environment.</p>
<p>Scientists have speculated that blue surfaces might look like <a href="https://royalsocietypublishing.org/doi/10.1098/rsbl.2003.0121">shaded places</a> to flies since shadows have a blueish tinge. Tsetse flies in particular seek out such shaded spots to rest in, which might explain their attraction to blue traps. </p>
<p>Another possibility is that blue surfaces might <a href="https://resjournals.onlinelibrary.wiley.com/doi/full/10.1046/j.1365-2915.1999.00163.x">lure hungry flies</a> by providing them with the telltale signs they use to distinguish animals against a background of foliage. According to this theory, a fly might mistake a blue trap for an animal it wishes to bite and feed upon. </p>
<figure class="align-left ">
<img alt="A blue canvas, diamond shaped container is suspended from a tree." src="https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535007/original/file-20230630-24873-ovj9iw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A bright blue trap for tsetse flies is suspended from a tree.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bright-blue-trap-dangerous-tsetse-fly-724357057">Fabian Plock/Shutterstock</a></span>
</figcaption>
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<p>But assessing these possibilities is especially tricky because flies perceive colour differently to people. Humans perceive colour using the responses of three kinds of light-detecting photoreceptor in the retina which are broadly sensitive to blue, green and red wavelengths of light.</p>
<p>But most “higher flies” – such as tsetse and horseflies – have five kinds of photoreceptor sensitive to UV, blue and green wavelengths. So, a blue trap won’t look the same to a fly as it does to the human who designed it.</p>
<h2>From flies to AI…</h2>
<p>In <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2023.0463#d1e1574">our study</a>, we tackled the problem by using artificial intelligence (AI). We used artificial neural networks which are a form of machine learning inspired by the structure of real nervous systems. Artificial neural networks learn by modifying the strengths of connections between a network of artificial neurons.</p>
<p>We fed these networks with the photoreceptor signals that a fly would experience when looking at animals or foliage backgrounds, both in light and in shade. We then trained the networks to distinguish animals from leaves, and shaded from unshaded objects, using only that visual information.</p>
<p>The trained networks would find the most efficient way of processing the visual signals, which we expected to share properties with the mechanisms that have evolved in real flies’ nervous systems. We then investigated whether the artificial neural networks classified blue traps as animals or as shaded surfaces.</p>
<h2>Blueness or brightness?</h2>
<p>After training, our neural networks could easily distinguish animals from leaf backgrounds, and shaded from unshaded stimuli, using the sensory information available to a fly. However, what surprised us was that they solved these problems in completely different ways.</p>
<p>The networks identified shade using brightness and not colour – quite simply, the darker a stimulus appeared, the more likely it was to be classified as shaded. Meanwhile, animals were identified using the relative strength of blue and green photoreceptor signals. Relatively greater blue compared to green signals indicated that a stimulus was probably an animal rather than a leaf, and vice versa.</p>
<p>The implications of this became clear when we fed these networks the visual signals caused by blue traps. The blue traps were never mistaken for shaded surfaces, but they were commonly misclassified as animals.</p>
<figure class="align-center ">
<img alt="A close up of an insect with huge blue/green eyes" src="https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535038/original/file-20230630-13700-zuvny9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The horse fly (<em>Hybomitra epistates</em>) can inflict painful bites upon people and livestock.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/horse-fly-hybomitra-epistates-portrait-1773555527">Mircea Costina/Shutterstock</a></span>
</figcaption>
</figure>
<p>Of course, artificial neural networks are not real flies, nor exact models of a fly’s nervous system. But they do show us the most efficient way of processing a fly’s visual signals to identify natural stimuli. And we expect evolution to have taken advantage of similar principles in real fly nervous systems.</p>
<p>The best way to identify shade using the visual information a fly has is through brightness and not blueness. Meanwhile, the best way of identifying animals was, somewhat counterintuitively, using blueness. Such a mechanism is very strongly stimulated by blue traps, explaining why they prove such a powerful lure for hungry flies. Further evidence for this idea comes from field studies which show that tsetse landing on coloured traps are <a href="https://resjournals.onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-3032.1990.tb00519.x">relatively starved</a>.</p>
<p>If we can understand the sensory signals and behaviour that cause flies to be caught in traps, we can engineer traps to more efficiently exploit those mechanisms and more effectively control the flies. We’ve already had <a href="https://journals.plos.org/plosntds/article?id=10.1371%2Fjournal.pntd.0007905#:%7E:text=Tsetse%20can%20be%20controlled%20using%20insecticide-treated%20fabric%20targets%2C,these%20fabrics%20to%20be%20more%20attractive%20to%20tsetse.">some success</a> in doing this for tsetse flies.</p>
<p>More effective traps will help minimise the impacts of those flies on health and welfare of people and animals. They could help prevent the damaging effects of biting flies on livestock, help in the fight against dangerous fly-borne diseases such as <a href="https://www.who.int/news-room/fact-sheets/detail/trypanosomiasis-human-african-(sleeping-sickness)">sleeping sickness</a>, and protect us and animals from fly attacks in general.</p><img src="https://counter.theconversation.com/content/208639/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Santer has received funding from the Knowledge Economy Skills Scholarships program, and from the Centre for International Development Research at Aberystwyth (CIDRA). </span></em></p>New research on what attracts blood-feasting flies to blue objects could help minimise the impacts of those insects on people and animals.Roger Santer, Lecturer in Zoology, Aberystwyth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1913112023-06-20T19:37:11Z2023-06-20T19:37:11ZFor some fire-loving insects, wildfires provide the best breeding grounds<iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/for-some-fire-loving-insects--wildfires-provide-the-best-breeding-grounds" width="100%" height="400"></iframe>
<p>With the summer solstice and first official day of summer on June 21, hot and dry conditions have already given rise to a <a href="https://globalnews.ca/news/9764583/canada-worst-wildfire-season-21st-century/">very active fire season across Canada</a>. </p>
<p>The smoke from these fires has drifted great distances, disrupting activities and causing a nuisance and breathing hazards in communities far from its source. </p>
<p>But, if you happen to be an insect adapted to wildfires, tracing the smoke back to its source is what you were born to do.</p>
<p>Many insects are attracted to wildfires and lay their eggs in the tissues of fire-killed trees. Some of these insects are wildfire specialists and colonize the area while the fire is still actively burning.</p>
<h2>Adaptations to forest fires</h2>
<p>Known as pyrophilic insects because of their affinity for wildfires, these insects locate and navigate to the fire using their highly sensitive sense of smell. The smoke <a href="https://doi.org/10.1117/12.882421">emitted from forest fires also provide important clues</a> about the tree species fuelling the fire and whether, or not, the trees are suitable hosts for the insects. </p>
<p>As a testament to their co-evolution with fire, some species, like the Australian fire beetle, have even evolved <a href="https://doi.org/10.1007/s001140050775">sensory organs capable of detecting infrared light</a> emitted from wildfires. These infrared sensors help the insects contend with the unpredictable and dangerous conditions of a typical wildfire, allowing them to avoid <a href="https://doi.org/10.1371/journal.pone.0192865">hot spots that might be lethal</a>. </p>
<p>About 50 to 60 known insect species are pyrophilic. <a href="https://doi.org/10.1016/j.foreco.2022.120629">This list</a> is made up mostly of beetles and flies but also includes a few true bugs and a single species of wasp called the <a href="https://doi.org/10.1093/aesa/60.6.1291">cedar wood wasp</a> (<em>Syntexis libocedrii</em>). </p>
<p>Little is known about their role in the ecosystem but some pyrophilic species help initiate recovery after the fire by breaking down decaying trees. Others are associated with pyrophilic fungi that are rarely found outside of recent burns. </p>
<p>Although a recent study suggests that some of these fungi are already <a href="https://doi.org/10.1016/j.funeco.2019.100870">present in a dormant state</a> when the fire erupts through, pyrophilic insects may also play a role in <a href="https://www.frames.gov/catalog/36861">transmission of pyrophilic fungi</a> to burns. These fungi provide a habitat for many insect species and assist in cycling nutrients that helps facilitate regrowth in the burn. </p>
<h2>Heat-sterilized soils</h2>
<p>Why these insects are the first to arrive at the fire only to disappear shortly after is also not well understood. However, <a href="https://doi.org/10.1002/ecs2.4213">new research</a> suggests that this peculiar behaviour may have evolved to increase offspring survival. </p>
<p>Forest soils are normally chalk-full of small micro-arthropods like mites that readily devour insect eggs. But the extreme heat from wildfires <a href="https://doi.org/10.1016/S0378-1127(00)00328-5">dramatically reduces invertebrate numbers in soils</a>, effectively sterilizing the soil. </p>
<p>Pyrophilic insects capitalize on this short window of opportunity and lay their eggs in the heat-sterilized soil before mites and other invertebrates recolonize the burn.</p>
<p>This temporary reprieve from egg predation explains part of why pyrophilic insects race to the fire. Comparing reproductive outputs in burnt and unburnt soils, the new study showed that this strategy can increase the number of offspring by 80 per cent.</p>
<p><a href="http://dx.doi.org/10.18195/issn.0312-3162.30(1).2015.001-011">Other studies</a> have also noted that the extreme heat and smoke of the active fire helps protect adults from predation during reproduction and egg-laying. </p>
<p>But once this window of opportunity closes, pyrophilic insects must seek out new fires and freshly burnt areas. This explains why, within just a year or two after the fire, the insects disappear from the burnt area.</p>
<h2>Unpredictable habitat</h2>
<p>The unpredictability of wildfires and the need to quickly locate them means pyrophilic insects are likely impacted when humans suppress wildfires. </p>
<p><a href="https://doi.org/10.1002/jqs.1242">Fossil evidence of pyrophilic insects</a> from <a href="https://doi.org/10.1016/S0031-0182(00)00188-7">regions like Britain where they are now rooted out of or extirpated</a>, for example, demonstrates the impact of human-induced changes to fire regimes.</p>
<p>Changes in land-use, fire suppression and the development of large industries like forestry and agriculture have <a href="https://doi.org/10.1890/ES11-00345.1">reduced wildfires in many regions</a>. At the same time, the current fire season as well as future projections of <a href="https://iopscience.iop.org/article/10.1088/1748-9326/aa5835">fire behaviour</a> under climate-warming suggests that available habitat for pyrophilic insects is likely to increase. </p>
<p>If the spring fire season in Canada is any indication, pyrophilic insects will continue to thrive well into summer.</p><img src="https://counter.theconversation.com/content/191311/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aaron Bell receives funding from the Government of Canada and Weston Family Foundation. </span></em></p>If the spring fire season in Canada is any indication, fire-loving pyrophilic insects will continue to thrive well into summer.Aaron Bell, Researcher, PhD Candidate, Biology, University of SaskatchewanLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2030962023-04-05T13:53:51Z2023-04-05T13:53:51ZEaster bunnies, cacao beans and pollinating bugs: A basket of 6 essential reads about chocolate<figure><img src="https://images.theconversation.com/files/519391/original/file-20230404-14-reloqo.jpg?ixlib=rb-1.1.0&rect=422%2C0%2C4914%2C3173&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Easter has its bunnies, but chocolate comes out for every holiday.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/chocolate-bunny-family-royalty-free-image/177875356">garytog/iStock via Getty Images Plus</a></span></figcaption></figure><p><a href="https://www.insider.com/surprising-easter-fun-facts-stats-2019-4#as-many-as-91-million-chocolate-bunnies-are-sold-in-the-us-for-easter-annually-8">Tens of millions of chocolate bunnies</a> get sold in the U.S. every Easter. Here are six articles about chocolate from The Conversation’s archive – great reading while you’re nibbling the ears off your own bunny (if you’re one of the <a href="https://www.insider.com/surprising-easter-fun-facts-stats-2019-4#as-many-as-78-of-americans-eat-the-ears-of-their-chocolate-bunny-first-11">three-quarters of Americans who start</a> at the top).</p>
<h2>1. Food scientist on cocoa chemistry</h2>
<p>Chocolate bunnies don’t grow on trees – but cacao pods do. It takes a lot of processing to get from the raw agricultural input to the finished output.</p>
<p>Food scientist <a href="https://scholar.google.com/citations?user=5iZjEckAAAAJ&hl=en&oi=ao">Sheryl Barringer</a> from The Ohio State University wrote about various chemical reactions that are part of the transformation of beans into chocolate. One is the Maillard reaction, the same thing that gives the browned bits on roasted meats or a bread’s golden crust their flavor. <a href="https://theconversation.com/chocolate-chemistry-a-food-scientist-explains-how-the-beloved-treat-gets-its-flavor-texture-and-tricky-reputation-as-an-ingredient-198222">Barringer also explains that weird white stuff</a> – known as bloom – that might appear on your Easter chocolates if they hang around for a while. (Don’t worry, it’s still edible.)</p>
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Read more:
<a href="https://theconversation.com/chocolate-chemistry-a-food-scientist-explains-how-the-beloved-treat-gets-its-flavor-texture-and-tricky-reputation-as-an-ingredient-198222">Chocolate chemistry – a food scientist explains how the beloved treat gets its flavor, texture and tricky reputation as an ingredient</a>
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<h2>2. Chocolate is a fermented food</h2>
<p>Food science Ph.D. candidate <a href="https://scholar.google.com/citations?user=QjIM6yUAAAAJ&hl=en&oi=ao">Caitlin Clark</a> from Colorado State University focuses her research on the microbes responsible for much of chocolate’s flavor. As a fermented food, chocolate depends on yeast and bacteria to help turn a raw ingredient into the treat you can recognize.</p>
<p>Clark described how the microorganisms that occur naturally in a given geographical location can give high-end chocolates their “terroir” – “<a href="https://theconversation.com/chocolates-secret-ingredient-is-the-fermenting-microbes-that-make-it-taste-so-good-155552">the characteristic flair imparted by a place</a>” you might be more used to thinking about with regard to wine.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/chocolates-secret-ingredient-is-the-fermenting-microbes-that-make-it-taste-so-good-155552">Chocolate's secret ingredient is the fermenting microbes that make it taste so good</a>
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<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Cacao pods and flowers on branch tree close up" src="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519395/original/file-20230404-2112-yh79aj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Tiny flies spread pollen from one cacao tree to another.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cacao-pods-and-flower-on-branch-royalty-free-image/1165785501">dimarik/iStock via Getty Images Plus</a></span>
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</figure>
<h2>3. Pollinators are important part of process</h2>
<p>Cacao growers rely on another tiny ally to pollinate their crop. Entomologist <a href="https://scholar.google.com/citations?hl=en&user=qvmWZYwAAAAJ">DeWayne Shoemaker</a> from the University of Tennessee described the mini flies – particularly biting midges and gall midges – that get the job done. “Pollinators must pick up pollen from the male parts of a flower of one tree and deposit it on the female parts of a flower on another tree,” Shoemaker wrote.</p>
<p>But up to <a href="https://theconversation.com/tiny-cacao-flowers-and-fickle-midges-are-part-of-a-pollination-puzzle-that-limits-chocolate-production-154334">90% of cacao flowers don’t get pollinated</a> at all. People can hand-pollinate the little flowers, but it remains a mystery which other insects might do the job in the wild.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/tiny-cacao-flowers-and-fickle-midges-are-part-of-a-pollination-puzzle-that-limits-chocolate-production-154334">Tiny cacao flowers and fickle midges are part of a pollination puzzle that limits chocolate production</a>
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<h2>4. Child labor is chocolate’s bitter secret</h2>
<p>Harvesting and processing cacao is labor-intensive. To meet this need, some farmers turn to child labor. Cultural anthropologist <a href="https://scholar.google.com/citations?user=1ErMxzgAAAAJ&hl=en&oi=ao">Robert Ulin</a> from the Rochester Institute of Technology described how the global chocolate industry is tied to inequality via exploitative labor practices.</p>
<p>“The largest chocolate companies signed a protocol in 2001 that <a href="https://theconversation.com/some-chocolate-has-a-dark-side-to-it-child-labor-179271">condemned child labor and childhood slavery</a>,” Ulin wrote. But he noted that consumers may want more information to make sure their purchase power supports “fair labor practices in the chocolate sector.” </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/some-chocolate-has-a-dark-side-to-it-child-labor-179271">Some chocolate has a dark side to it – child labor</a>
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<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dog and woman, both with Easter bunny ears on" src="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519398/original/file-20230404-18-7hqbi6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Do not share your chocolates with your pooch.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/dog-and-woman-with-costume-and-easter-decorations-royalty-free-image/1359250422">F.J. Jimenez/Moment via Getty Images</a></span>
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<h2>5. Not safe for furry family members</h2>
<p>Eating a ton of chocolate is probably not a healthy choice for anyone. But even a little bit of chocolate can be deadly for dogs and cats. </p>
<p>In an article about all kinds of holiday foods that are unsafe for pets, veterinarian and researcher <a href="https://experts.okstate.edu/le.fanucchi">Leticia Fanucchi</a> from Oklahoma State University explained the chemicals in this human delicacy that can cause fatal “<a href="https://theconversation.com/holiday-foods-can-be-toxic-to-pets-a-veterinarian-explains-which-and-what-to-do-if-rover-or-kitty-eats-them-196453">chocolate intoxication</a>.” Don’t delay getting veterinary help if your pet does raid your Easter basket.</p>
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Read more:
<a href="https://theconversation.com/holiday-foods-can-be-toxic-to-pets-a-veterinarian-explains-which-and-what-to-do-if-rover-or-kitty-eats-them-196453">Holiday foods can be toxic to pets – a veterinarian explains which, and what to do if Rover or Kitty eats them</a>
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<h2>6. An enslaved chocolatier in colonial America</h2>
<p>An enslaved cook named Caesar, born in 1732, was one of the first chocolatiers in the American colonies. Historical archaeologist <a href="https://berkeley.academia.edu/KelleyFantoDeetz">Kelley Fanto Deetz</a> from the University of California, Berkeley described how Caesar “would have had to <a href="https://theconversation.com/oppression-in-the-kitchen-delight-in-the-dining-room-the-story-of-caesar-an-enslaved-chef-and-chocolatier-in-colonial-virginia-151356">roast the cocoa beans on the open hearth</a>, shell them by hand, grind the nibs on a heated chocolate stone, and then scrape the raw cocoa, add milk or water, cinnamon, nutmeg or vanilla, and serve it piping hot.”</p>
<p>Cocoa was a hot commodity for Virginia’s white elite during this period, when it was a culinary component – along with pineapples, Madeira wine, port, champagne, coffee and sugar – of the Columbian Exchange.</p>
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<em>
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Read more:
<a href="https://theconversation.com/oppression-in-the-kitchen-delight-in-the-dining-room-the-story-of-caesar-an-enslaved-chef-and-chocolatier-in-colonial-virginia-151356">Oppression in the kitchen, delight in the dining room: The story of Caesar, an enslaved chef and chocolatier in Colonial Virginia</a>
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<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p><img src="https://counter.theconversation.com/content/203096/count.gif" alt="The Conversation" width="1" height="1" />
Two food scientists, an entomologist, an anthropologist, a veterinarian and a historian walk into a bar (of chocolate) and tell bitter and sweet stories of this favorite treat.Maggie Villiger, Senior Science + Technology EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1870512022-08-17T12:38:53Z2022-08-17T12:38:53ZFlies evade your swatting thanks to sophisticated vision and neural shortcuts<figure><img src="https://images.theconversation.com/files/478807/original/file-20220811-20-9x44dv.jpg?ixlib=rb-1.1.0&rect=22%2C29%2C4966%2C3485&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fly brains can process images very quickly.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/house-fly-royalty-free-image/535501923">www.shutterexperiments.com/Moment via GettyImages</a></span></figcaption></figure><p>Sitting outside on a summer evening always sounds relaxing until flies and mosquitoes arrive – then the swatting begins. Despite their minuscule eyes and a <a href="https://www.fruitflybrain.org/#/">brain</a> roughly <a href="https://www.hhmi.org/news/complete-fly-brain-imaged-at-nanoscale-resolution">1 million times</a> smaller than yours, flies can evade almost every swat. </p>
<p>Flies can thank their fast, sophisticated eyesight and some neural quirks for their ability to escape swats with such speed and agility.</p>
<p><a href="https://scholar.google.com/citations?hl=en&user=4i4wRGgAAAAJ">Our lab</a> <a href="https://scholar.google.com/citations?user=WBxN0p4AAAAJ&hl=en&oi=ao">investigates insect flight and vision</a>, with the goal of finding out how such tiny creatures can process visual information to perform challenging behaviors, such as escaping your swatter so quickly.</p>
<h2>Faster vision</h2>
<p>Flies have compound eyes. Rather than collecting light through a single lens that makes the whole image – the strategy of human eyes – flies form images built from multiple <a href="https://doi.org/10.1007/978-3-642-74082-4_3">facets</a>, lots of individual lenses that focus incoming light onto clusters of photoreceptors, the light-sensing cells in their eyes. Essentially, each facet produces an individual pixel of the fly’s vision. </p>
<p>A fly’s world is fairly low resolution, because small heads can house only a limited number of facets – usually <a href="https://www.jstor.org/stable/24954051">hundreds to thousands</a> – and there is no easy way to sharpen their blurry vision up to the millions of pixels people effectively see. But despite this coarse resolution, flies see and process fast movements very quickly.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/478805/original/file-20220811-23-9ejxvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of a fly eye, showing tiny hexagonal facets and the photoreceptor layer under these facets." src="https://images.theconversation.com/files/478805/original/file-20220811-23-9ejxvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/478805/original/file-20220811-23-9ejxvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=378&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478805/original/file-20220811-23-9ejxvf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=378&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478805/original/file-20220811-23-9ejxvf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=378&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478805/original/file-20220811-23-9ejxvf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=475&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478805/original/file-20220811-23-9ejxvf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=475&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478805/original/file-20220811-23-9ejxvf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=475&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Tiny hexagonal ‘facets’ take in light, and the photoreceptors beneath them process it in quick flashes.</span>
<span class="attribution"><a class="source" href="https://www.epfl.ch/labs/lis/research/completed/curvace/">Ecole Polytechnique Fédérale de Lausanne, Switzerland</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>We can infer how animals perceive fast movement from how quickly their photoreceptors can process light. Humans discern a maximum of <a href="https://www.mdpi.com/1648-9144/57/10/1096/htm">about 60 discrete flashes</a> of light per second. Any faster usually appears as steady light. The ability to see discrete flashes depends on the lighting conditions and which part of the retina you use. </p>
<p>Some LED lights, for example, emit discrete flashes of light quickly enough that they appear as steady light to humans – unless you turn your head. In your peripheral vision you may notice a flicker. That’s because your peripheral vision processes light more quickly, but at a lower resolution, like fly vision. </p>
<p>Remarkably, some flies can see as many as <a href="https://doi.org/10.2307/1539540">250 flashes per second</a>, around four times more flashes per second than people can perceive. </p>
<p>If you took one of these flies to the cineplex, the smooth movie you watched made up of 24 frames per second would, to the fly, appear as a series of static images, like a slide show. But this fast vision allows it to react quickly to prey, obstacles, competitors and your attempts at swatting.</p>
<p><a href="https://faculty.fiu.edu/%7Etheobald/">Our research</a> shows that flies <a href="https://doi.org/10.1016/j.visres.2020.02.007">in dim light lose some ability to see fast movements</a>. This might sound like a good opportunity to swat them, but humans also lose their ability to see quick, sharp features in the dark. So you may be just as handicapped your target. </p>
<p>When they do fly in the dark, flies and mosquitoes <a href="https://doi.org/10.1016/j.cub.2022.01.078">fly erratically</a>, with twisty flight paths to escape swats. They can also rely on <a href="https://doi.org/10.1016/bs.aiip.2016.04.007">nonvisual cues</a>, such as information from small hairs on their body that sense changes in the air currents when you move to strike.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/9wqZ7Jt3thg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Flight of a mosquito. Source: Intellectual Ventures.</span></figcaption>
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<h2>Neural tricks</h2>
<p>But why do flies see more slowly in the dark? You may have noticed your own vision becoming sluggish and blurry in the dark, and much less colorful. The process is similar for insects. Low light means <a href="https://doi.org/10.1098/rstb.2016.0062">fewer photons</a>, and just like cameras and telescopes, eyes depend on photons to make images. </p>
<p>But unlike a nice camera, which allows you to switch to a larger lens and gather more photons in dark settings, animals can’t swap out the optics of their eyes. Instead, they rely on <a href="https://doi.org/10.1016/S0042-6989(98)00262-4">summation</a>, a neural strategy that adds together the inputs of neighboring pixels, or increases the time they sample photons, to form an image.</p>
<p>Big pixels and longer exposures capture more photons, <a href="https://faculty.fiu.edu/%7Etheobald/visual-pooling/">but at the cost of sharp images</a>. Summation is equivalent to taking photographs with grainy film (higher ISO) or slow shutter speeds, which produce blurrier images, but avoid <a href="https://www.youtube.com/watch?v=eAhEatlueXA">underexposing</a> your subjects. Flies, <a href="https://doi.org/10.1016/j.visres.2018.05.007">especially small ones</a>, can’t see quickly in the dark because, in a sense, they are waiting for enough photons to arrive until they are sure of what they are seeing.</p>
<h2>Flight maneuverability</h2>
<p>In addition to rapidly perceiving looming threats, flies need to be able to fly away in a split second. This requires preparation for takeoff and <a href="https://doi.org/10.1126/science.1248955">quick flight maneuvers</a>. After visually detecting a looming threat, fruit flies, for example, adjust their posture in <a href="https://doi.org/10.1016/j.cub.2008.07.094">one-fifth of a second</a> before takeoff. Predatory flies, such as <a href="https://doi.org/10.1159/000435944">killer flies</a>, coordinate their legs, wings and halteres – dumbbell-shaped remnants of wings used for sensing in-air rotations – to quickly catch their prey midflight. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/tkK63pHFML0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Flight of a fly. Notice how they adjust their posture before takeoff. Source: The New York Times.</span></figcaption>
</figure>
<h2>How best to swat a fly</h2>
<p>To outmaneuver a fly, you must strike faster than it can detect your approaching hand. With practice, you may improve at this, but flies have honed their escapes over hundreds of millions of years. So instead of swatting, using other ways to manage flies, such as installing fly traps and cleaning backyards, is a better bet. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/OEIk_68miZc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Escape behavior of a fly in slow motion. Source: Florian Muijres et al, 2014 Science.</span></figcaption>
</figure>
<p>You can lure certain flies into a narrow neck bottle filled with apple cider vinegar and beer. Placing a funnel in the bottle neck makes it easy for them to enter, but difficult to escape. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/478976/original/file-20220812-1219-4t7yzv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A simple home-made fruit fly trap" src="https://images.theconversation.com/files/478976/original/file-20220812-1219-4t7yzv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/478976/original/file-20220812-1219-4t7yzv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=854&fit=crop&dpr=1 600w, https://images.theconversation.com/files/478976/original/file-20220812-1219-4t7yzv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=854&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/478976/original/file-20220812-1219-4t7yzv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=854&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/478976/original/file-20220812-1219-4t7yzv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1074&fit=crop&dpr=1 754w, https://images.theconversation.com/files/478976/original/file-20220812-1219-4t7yzv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1074&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/478976/original/file-20220812-1219-4t7yzv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1074&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Apple cider vinegar and beer trap to control fruit flies in your kitchen or backyard.</span>
<span class="attribution"><span class="source">Ravindra Palavalli-Nettimi</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>As for mosquitoes, some commercial repellents may work, but removing stagnant water around the house – in some plants, pots or any open containers – will help <a href="https://www.cdc.gov/mosquitoes/mosquito-control/athome/outside-your-home/index.html">eliminate their egg-laying sites</a> and reduce the number of mosquitoes around from the start. Avoid insecticides, as they also <a href="https://environment-review.yale.edu/deadlier-intended-pesticides-might-be-killing-beneficial-insects-beyond-their-targets-0">harm useful insects</a> such as bees and butterflies.</p><img src="https://counter.theconversation.com/content/187051/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jamie Theobald receives funding from the National Science Foundation (IOS-1750833). </span></em></p><p class="fine-print"><em><span>Ravindra Palavalli-Nettimi does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Why is it so difficult to swat a fly? A team of insect experts explains how a fly’s sophisticated vision allows it to quickly react to visual cues.Jamie Theobald, Associate Professor of Biological Sciences, Florida International UniversityRavindra Palavalli-Nettimi, Postdoctoral Research Associate, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1769812022-02-28T19:14:05Z2022-02-28T19:14:05ZFlies, maggots and methamphetamine: how insects can reveal drugs and poisons at crime scenes<figure><img src="https://images.theconversation.com/files/448798/original/file-20220228-4024-xsiszf.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C2389%2C1580&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The oldest book of zoology was <a href="https://en.wikipedia.org/wiki/Urra%3Dhubullu">published on clay tablets more than 3,600 years ago</a>, and reported the names of 396 types of wild animals known at the time. Ten of them were different kinds of fly. </p>
<p>Flies have lived alongside humans since the dawn of history, feeding on our bodily fluids and other organic waste such as meat and vegetable scraps. When an adult female blowfly finds some juicy decaying material – typically a carcass – she may lay hundreds of eggs or tiny maggots in it.</p>
<p>So flies use us, our products, our waste, and even the bodies of our dead. How can we use them in return?</p>
<p>One way is <a href="https://pubmed.ncbi.nlm.nih.gov/14991142/">the science of forensic entomology</a>. At a crime scene, flies and maggots can be used to determine how long it has been since a person or animal died, if they have been moved or neglected prior to death – and what drugs or poisons they had in their system.</p>
<h2>From flies on a sickle to modern forensics</h2>
<p>The first recorded instance of flies helping out in a murder case was during the 13th century. </p>
<p>A Chinese judge named <a href="https://en.wikipedia.org/wiki/Song_Ci">Sung T'zu</a> was sent to investigate a fatal stabbing in a rice field. </p>
<p>At the scene of the murder, he asked all the workers to lay down their sickles. After a short time, several flies swarmed on one of the sickles, attracted by the smell of invisible traces of blood. </p>
<p>Sung T'zu wrote about the case in <a href="https://www.jstor.org/stable/10.3998/mpub.19945">The Washing Away of Wrongs</a>, the oldest known book on forensic medicine, printed in 1247. He showed how thinking “outside the box” using clues from nature can help in forensic investigations. </p>
<p>It was several more centuries before the scientific method was applied to the use of flies in criminal investigations. The discipline of forensic entomology as we know it was not born until 1894, with the publication of <a href="https://collections.nlm.nih.gov/catalog/nlm:nlmuid-28421710R-bk">Carrion Fauna: The Application of Entomology to Legal Medicine</a>, by the French army veterinarian and entomologist Jean Pierre Mégnin.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/meet-the-maggot-how-this-flesh-loving-butt-breathing-marvel-helps-us-solve-murders-166518">Meet the maggot: how this flesh-loving, butt-breathing marvel helps us solve murders</a>
</strong>
</em>
</p>
<hr>
<p>Since then, research on blowfly growth rates, decomposition patterns in different environments and use of blowflies to clean up the wounds (<a href="https://pubmed.ncbi.nlm.nih.gov/32825736/">debridement or “maggot” therapy</a>) have gained momentum. </p>
<p>Often flies can help estimate the time of death, as an entomologist can identify the flies or maggots, look at environmental conditions such as temperature, and thereby calculate the amount of time they have been growing.</p>
<p>Forensic entomologists are often involved at crime scenes, and <a href="https://pubmed.ncbi.nlm.nih.gov/9670502/">many suspicious deaths of humans and animals</a> have been solved with the help of insects. </p>
<h2>You are what you eat</h2>
<p>However, drugs and poisons can also affect how attractive blowflies find the carcass, and how quickly maggots grow on it. This means we often need to identify what drugs or poisons we are dealing with.</p>
<p>This can be found by analysing blood, urine, solid tissue or hairs from the dead body. But in some cases all that remains is a skeleton, so these are unavailable.</p>
<p>In these cases, we need to think outside the box, just like Sung T'zu. The old adage says “you are what you eat”, so insects feeding on a body should take in substances from the body and store them in their own bodies.</p>
<p>Furthermore, insects’ hard external skeleton is made of chitin, a comparable substance to the keratin protein from which hair is made. Similarly to hair keratin, insect chitin stores drugs for a long time, which is helpful for toxicological analyses. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/448804/original/file-20220228-23-ls9wc8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/448804/original/file-20220228-23-ls9wc8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/448804/original/file-20220228-23-ls9wc8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/448804/original/file-20220228-23-ls9wc8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/448804/original/file-20220228-23-ls9wc8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/448804/original/file-20220228-23-ls9wc8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/448804/original/file-20220228-23-ls9wc8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Insect exoskeletons are made of chitin, a substance that stores traces of drugs for a long time.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Insects collected from a carcass can be used as alternative toxicological specimens in situations where traditional sources are not available. Knowing the effect of the toxins on the life cycles of the flies can be used to adjust what we know about their growth rates.</p>
<p>In the early 1970s, the Finnish biologist Pekka Nuorteva showed <a href="https://www.jstor.org/stable/23731650">mercury from a fish carcass could transfer to carrion flies</a>. A few years later a similar analysis was used to determine whether a murder victim had lived in a polluted area. By 1977 the hybrid discipline of entomotoxicology (entomology + toxicology) became a reality. </p>
<p>When tissues and fluids are unavailable, insects are more reliable than hair to detect drug use just before death. They are also easier to analyse than decomposed matter. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mummies-have-had-a-bad-wrap-its-time-for-a-reassessment-48729">Mummies have had a bad wrap – it's time for a reassessment</a>
</strong>
</em>
</p>
<hr>
<p>What’s more, they are available for a very long time. Empty fly puparial cases (cocoons left in the environment by the adult fly after its metamorphosis) as well as skin of carrion beetles have even been used for <a href="https://academic.oup.com/jme/article/52/5/755/831468?login=false">toxicological studies</a> of <a href="https://www.ojp.gov/ncjrs/virtual-library/abstracts/isolation-amitriptyline-and-nortriptyline-fly-puparia-phoridae-and">mummified bodies</a> found weeks, months, or even years after death. </p>
<p>And since <a href="https://www.sciencedirect.com/science/article/abs/pii/037907389390280N">cocaine has been detected in the hair of
3,000-year-old Peruvian mummies</a>, it might also be possible to detect drugs in the insects associated with ancient skeletal remains.</p>
<h2>Ice and antifreeze</h2>
<p>Since the beginning of the COVID-19 pandemic, there has been an <a href="https://www.commonwealthfund.org/blog/2022/overdose-deaths-surged-first-half-2021-underscoring-urgent-need-action">increase in drug overdose deaths</a> and also <a href="https://www.aaha.org/publications/newstat/articles/2020-07/big-spike-in-pandemic-related-pet-poisonings/">pet poisonings</a>. </p>
<p>My research group is developing ways to detect a range of drugs and other substances commonly found in the suspicious death of humans and animals.</p>
<p>One of these is <a href="https://pubmed.ncbi.nlm.nih.gov/24905151/">methamphetamine</a>, a large problem for Australian law enforcement and health authorities. Another is <a href="https://pubmed.ncbi.nlm.nih.gov/29753971/">ketamine</a>, a sedative and hallucinogen sometimes used to facilitate sexual assault. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ice-age-the-rise-of-crystal-meth-in-australia-26052">Ice age: the rise of crystal meth in Australia</a>
</strong>
</em>
</p>
<hr>
<p>We have also studied the effect of cheap, dangerous, and readily available poisons on blowflies, including</p>
<ul>
<li><p><a href="https://pubmed.ncbi.nlm.nih.gov/26874739/">nicotine</a>, which can be lethal if ingested from e-cigarette refills or if passed through the skin via nicotine patches</p></li>
<li><p><a href="https://pubmed.ncbi.nlm.nih.gov/29526269/">car antifreeze</a> (ethylene glycol), as it is sometimes used to make home-made alcoholic drinks or consumed by homeless people in winter in the hope to keep themselves warm at night</p></li>
<li><p><a href="https://academic.oup.com/jme/article/55/1/51/4344943">endosulfan</a>, a pesticide often used to make poison baits to kill animals.</p></li>
</ul>
<h2>More to be done</h2>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/21237593/">Many compounds (such as drugs, metals and pesticides)</a> as well as <a href="https://pubmed.ncbi.nlm.nih.gov/28567525/">accelerants and gunshot residues</a> have been detected in insect tissues in a forensic context. However, fewer than 100 such studies have been carried out.</p>
<p>Furthermore, older research often lacks consistency, robust study protocols and method validations. Standard protocols and more sophisticated analytical methods can provide more accurate results that will hold more weight in court.</p><img src="https://counter.theconversation.com/content/176981/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paola A. Magni does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Forensic entomologists analyse blowflies and cocoon cases to help solve crimes.Paola A. Magni, Senior Lecturer in Forensic Science, Murdoch UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1764692022-02-11T04:10:05Z2022-02-11T04:10:05ZMarch flies prowl Australia’s beaches looking for blood – but why?<figure><img src="https://images.theconversation.com/files/445585/original/file-20220210-18440-1g43cw4.JPG?ixlib=rb-1.1.0&rect=0%2C3%2C2272%2C1697&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>While relaxing at the coast this summer, you might have noticed a few fellow beach goers failing to socially distance. You might even have had the unpleasant experience of one biting you and drawing blood. </p>
<p>Australia’s large buzzing flies – commonly called march flies – are very quick to home in on napping sunbathers, looking for a meal of blood. But what are they actually doing on our beaches, given we’re seemingly the only large animals there? </p>
<p>The answer: breeding. Female march flies use your blood to boost their egg production. Then they lay eggs in the sand. After hatching, the hungry maggots wait for prey under your feet. </p>
<p>In large enough numbers, these flies can make beachgoing downright unpleasant. But there are ways to protect yourself. Wearing vertical stripes confuses them, and thicker clothes are harder to bite through. Put a towel over your body while you nap. </p>
<h2>The largest of all bloodsucking insect families</h2>
<p>The flies ruining your beach outing are mostly members of the family Tabanidae, the horse, deer, and march flies. Globally, there are around <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/syen.12145">4,600 species</a> of these fast, alert flies. That makes tabanid flies the lineage with the most species of all bloodsucking insects, more diverse than mosquitoes, fleas, or lice. About <a href="https://www.publish.csiro.au/ZO/ZO9540431">500 species</a> are endemic to Australia, with dozens of species left to describe. They are diverse and plentiful, ranging from our highest mainland peak, Mount Kosciuszko, down to sea level. </p>
<p>Tabanid flies have streamlined bodies with eyes taking up most of their heads. Individual parts of their eyes can be <a href="https://www.sciencedirect.com/science/article/pii/0022191091900636">sized or coloured differently</a> to filter light, giving them clearer focus on contrast and shadow. Their antennae are strong and sensitive. These flies can <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/mve.12038">detect everything </a>from the carbon dioxide we exhale to octenol, a key component of our sweat and breath, as well urine. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/445859/original/file-20220211-23-dn4w93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="march fly close up" src="https://images.theconversation.com/files/445859/original/file-20220211-23-dn4w93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445859/original/file-20220211-23-dn4w93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445859/original/file-20220211-23-dn4w93.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445859/original/file-20220211-23-dn4w93.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445859/original/file-20220211-23-dn4w93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445859/original/file-20220211-23-dn4w93.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445859/original/file-20220211-23-dn4w93.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The face of a march fly.</span>
<span class="attribution"><span class="source">Getty Images</span></span>
</figcaption>
</figure>
<h2>Why are they on my beach?</h2>
<p>You might look up and down a salty, windswept beach and wonder where these flies are coming from. And what do they feed on after school holidays are over?</p>
<p>Well, beaches are just one of the micro-habitats where land meets sea. Many invertebrates take advantage of these areas due to the mix of resources. While they might look desolate, beaches are important for many bird and marsupial species. Some <a href="https://www.awe.gov.au/environment/biodiversity/threatened/recovery-plans/national-recovery-plan-proserpine-rock-wallaby-petrogale-persephone#:%7E:text=Species%20and%20current%20status,for%20the%20Proserpine%20rock%2Dwallaby.">wallaby species</a> only live on coastal habitats. </p>
<p>So while you might not see other possible meals for march flies, they sure do. Adept and manoeuvrable <a href="https://academic.oup.com/aesa/article/77/3/293/310623?login=true">in flight</a>, march flies <a href="https://academic.oup.com/ee/article/16/1/211/413707?login=true">travel kilometres</a> in search of blood meals. They are not picky and most will bite any vertebrate they can find.</p>
<p>It’s only the female march flies who are out for your blood. Both females and males also rely on nectar, visiting the flowering plants in beach dune systems. </p>
<p>Not all march fly species need blood. While protein in blood boosts egg production, some species can produce a smaller clutch of eggs using only nectar and larval resources. One beach dune subfamily, <a href="https://www.publish.csiro.au/ZO/ZO9550583">Scepsidinae</a>, has no functional mouthparts as adults. The food they eat during their rich larval stage is ample.</p>
<figure class="align-center ">
<img alt="Seven march fly maggots writhing on a human palm" src="https://images.theconversation.com/files/445605/original/file-20220210-26283-1nbjpz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445605/original/file-20220210-26283-1nbjpz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445605/original/file-20220210-26283-1nbjpz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445605/original/file-20220210-26283-1nbjpz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445605/original/file-20220210-26283-1nbjpz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445605/original/file-20220210-26283-1nbjpz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445605/original/file-20220210-26283-1nbjpz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Larvae of the march fly species <em>dasybasis exulans</em> found in beach sand.</span>
<span class="attribution"><span class="source">David Ferguson</span></span>
</figcaption>
</figure>
<h2>What’s worse than biting march flies? Their predatory maggots.</h2>
<p>March flies spend most of their lives as legless predatory maggots hiding underground. Covered in warty armour and fleshy tubercles, these maggots are voracious predators of soil fauna. To subdue their prey, they have long fangs with venom canals. </p>
<p>If that description makes you think of Dune’s giant sandworms, you’re not far off. Tabanid maggots have been seen <a href="https://www.nytimes.com/1983/10/29/us/at-scientists-feet-horseflies-eating-toads.html">pulling down toads</a> as they rest on the surface. </p>
<p>While adults have broad tastes, the larvae are specialised predators operating in specific micro-habitats. In fact, larval adaptation to soil type and humidity has likely contributed to the species richness of Tabanidae. Within each small niche, the maggots are fearsome. </p>
<p>Take <a href="https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-021-01088-z">mangroves</a>, which are nearly as rich in fly species as rainforests. The roots of sand dune plants also host insect, crustacean and worms, which the maggots prey on. Nowhere in these coastal systems is safe from them. They can find prey in the muddy divots among dunes and even go down to the waves’ edge. </p>
<p>Many flies have adapted to be able to eat seaweed and marine life washing in on the tide. But as these different fly species land, march fly maggots may well be there waiting beneath the sand for the first brave arrivals. It is likely many more species of larvae are growing under our feet, as yet unknown to science. The first we know of the great drama below ground is when the maggots pupate into hungry and clever adults.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/445606/original/file-20220210-26283-ufn6rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="View along a beach looking at headland with a shovel showing efforts to dig maggots out of the dune" src="https://images.theconversation.com/files/445606/original/file-20220210-26283-ufn6rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/445606/original/file-20220210-26283-ufn6rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/445606/original/file-20220210-26283-ufn6rr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/445606/original/file-20220210-26283-ufn6rr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/445606/original/file-20220210-26283-ufn6rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/445606/original/file-20220210-26283-ufn6rr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/445606/original/file-20220210-26283-ufn6rr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ideal habitat for march fly maggots.</span>
<span class="attribution"><span class="source">David Ferguson</span></span>
</figcaption>
</figure>
<h2>How can we avoid them?</h2>
<p>Most people would like to avoid being feasted on by adult march flies while on the beach. There’s no simple fix, alas. These flies can easily <a href="https://link.springer.com/article/10.1007/s00114-008-0425-5">see polarised light </a> and dark colours contrasting with sand and vegetation. Their painful bites can penetrate light fabrics. </p>
<p>Heavier fabrics, including rashies and stinger suits, can provide some protection. And if that fails, try wearing stripes. Recent studies suggest march flies are baffled by vertical stripes, which is one reason zebras are <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0223447&fbclid=IwAR15EQwhHFGOeE6YB6tvEV2Ue_UJ-RQ3Az_-UW3QJrVtiQ">coloured as they are</a>. </p>
<p>Insect repellents with DEET can provide some reprieve, though the flies are so fast they can zoom in for a nip before being repelled. So what can we do? Luckily, the flies tend to settle for a moment before biting. That’s your best opportunity to shoo them away.</p>
<p>March flies are worst in the warmer months, particularly on clear, sunny days without wind. In humid regions, they can stay active over winter too. Thankfully, tabanid flies are not involved in human disease transmission in Australia, though their bites can cause <a href="https://ww2.health.wa.gov.au/Articles/J_M/March-flies">allergic reactions</a> and they can carry pathogens to <a href="https://www.sciencedirect.com/science/article/pii/S1567134821004524">kangaroos and wallabies</a>. </p>
<p>You’ll notice that some beaches are plagued by march flies and others have barely any. In our years of researching flies, we’ve found march flies and other tabanid flies to be at their most annoying on remote beaches with natural bushland. Take a moment to appreciate their aerodynamic adaptations before moving to another beach.</p><img src="https://counter.theconversation.com/content/176469/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Yeates currently receives funding from CSIRO and The Schlinger Trust. </span></em></p><p class="fine-print"><em><span>Keith M. Bayless works for CSIRO. He is a recipient of Schlinger Trust funds at the Australian National Insect Collection.</span></em></p>The painful bites of female march flies can ruin your day at the beach. When we’re not there, they bite wallabies, birds, and even reptiles.David Yeates, Director of the Australian National Insect Collection, CSIROKeith M. Bayless, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1685492021-11-08T13:43:51Z2021-11-08T13:43:51ZDo flies really throw up on your food when they land on it?<figure><img src="https://images.theconversation.com/files/423207/original/file-20210925-14-1yipuw9.jpg?ixlib=rb-1.1.0&rect=115%2C121%2C3765%2C2445&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fly regurgitating digestive juices.</span> <span class="attribution"><span class="source">Carlos Ruiz</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>Do flies really throw up on my food when they land on it? – Henry E., age 10, Somerville, Massachusetts</strong></p>
</blockquote>
<hr>
<p>Imagine you’re at a picnic and just about to bite into your sandwich. Suddenly you spot a fly headed your way, homing in on your food with help from its <a href="https://askentomologists.com/2015/02/25/through-the-compound-eye/">compound eyes</a> and antennae. It manages to escape your swatting, lands on the sandwich and then seems to throw up on it!</p>
<p>It can look kind of gross, but the fly might be just airing out its own digested food, or <a href="https://doi.org/10.1093/aesa/90.2.184">spitting on yours</a>.</p>
<p>Most of the <a href="https://www.si.edu/spotlight/buginfo/true-flies-diptera">over 110,000</a> known fly species <a href="https://doi.org/10.1673/031.008.7301">have no teeth</a>, so they cannot chew solid food. Their mouthparts are like a spongy straw. Once they land on your food, they need to release digestive juices to liquefy it into a predigested, slurpable soup they can swallow. In short, some flies are on a <a href="https://doi.org/10.1673/031.008.7301">liquid diet</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/N23E4jYTExk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A fly slurping its liquid meal.</span></figcaption>
</figure>
<p>To fit more food in their stomachs, some flies try to reduce the liquid in what they have already eaten. They regurgitate food into vomit bubbles to dry it out a bit. Once <a href="https://doi.org/10.1111/j.1365-3032.1992.tb01193.x">some water has evaporated</a> they can ingest this more concentrated food. </p>
<p>Human beings don’t need to do all this spitting and regurgitating to get nutrients out of our food. But you do produce a digestive juice in your saliva, an enzyme called <a href="https://1md.org/health-guide/digestive/ingredients/alpha-amylase">amylase</a>, which predigests some of the sandwich bread while you chew. Amylase breaks down starch, which you can’t taste, into simple sugars like glucose, which you can taste. That’s why <a href="https://doi.org/10.1093/chemse/bjz010">bread gets sweeter</a> the longer you chew it. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="closeup of a reddish insect with bristly black hairs on its body" src="https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=577&fit=crop&dpr=1 754w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=577&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/423212/original/file-20210925-23-18a0vfd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=577&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bristles and hair on a Tachinid fly.</span>
<span class="attribution"><span class="source">Maria Cleopatra Pimienta</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Did you know flies can taste food without their mouths? As soon as they land, they use receptors on their feet to decide whether they’re on something nutritious. You may have noticed a fly rubbing its legs together, like a hungry customer getting ready to devour a meal. <a href="https://doi.org/10.1016/j.cub.2020.01.045">This is called grooming</a> – the fly is essentially cleaning itself, and may also clean the <a href="https://doi.org/10.1016/j.conb.2009.07.001">taste sensors</a> on the <a href="https://doi.org/10.1523/JNEUROSCI.0649-14.2014">bristles and fine hair of its feet</a>, to get a better idea of what is in the food it has landed on.</p>
<h2>Should you trash food a fly’s landed on?</h2>
<p>When a fly touches down on your sandwich, that’s probably not the only thing it’s landed on that day. Flies often sit on gross stuff, like a dumpster or decomposing food, that’s full of microbes. The germs can hitch a ride and, if the fly stays put long enough, hop onto your meal. This is much more dangerous than their saliva because <a href="https://doi.org/10.1038/s41598-017-16353-x">some of the microbes</a> can cause diseases, like <a href="https://doi.org/10.1016/j.vaccine.2019.07.078">cholera</a> and <a href="https://doi.org/10.1353/pbm.2006.0005">typhoid</a>. But if the fly doesn’t stay longer than a few seconds the <a href="https://theconversation.com/should-i-throw-away-food-once-a-fly-has-landed-on-it-50895">chances of microbes transferring are low</a>, and your food is probably fine. </p>
<p>To keep insects from landing on your food, you should always cover it. If your house is infested with flies, you can use <a href="https://theconversation.com/how-to-kill-fruit-flies-according-to-a-scientist-81740">simple traps</a> to get rid of them. Carnivorous plants can also eat the flies and help control their population.</p>
<h2>Are flies good for anything?</h2>
<p>Spitting on food and spreading diseases sounds disgusting, but flies aren’t all bad. </p>
<p>Watch closely the next time you’re outside and you might be surprised by how many flies visit flowers to get nectar. They’re an important group of <a href="https://doi.org/10.3390/insects11060341">pollinators</a>, and many plants need flies to <a href="https://theconversation.com/tiny-cacao-flowers-and-fickle-midges-are-part-of-a-pollination-puzzle-that-limits-chocolate-production-154334">help them reproduce</a>.</p>
<p>Flies are also a good source of food for frogs, lizards, spiders and birds, so they’re a valuable <a href="https://doi.org/10.1002/ps.5807">part of the ecosystem</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="doctor working on patient's foot in background, tubes of maggots in foreground" src="https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=422&fit=crop&dpr=1 600w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=422&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=422&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=531&fit=crop&dpr=1 754w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=531&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/429602/original/file-20211101-25-1rfhnd6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=531&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A doctor uses sterile maggots like those in these tubes to clean a patient’s foot wound.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/steril-gezüchtete-maden-im-vordergrund-in-reagenzgläsern-zu-news-photo/1213178783">Norbert Försterling/picture alliance via Getty Images</a></span>
</figcaption>
</figure>
<p>Some <a href="https://doi.org/10.1134/S0013873819030023">flies have medical uses</a>, too. For example, doctors use blow fly maggots – the young, immature form of flies – to remove decomposing tissue in wounds. The maggots release antiviral and antimicrobial juices, and these have helped scientists create new treatments for infections.</p>
<p>More importantly, the fruit flies you may have seen flying around ripe bananas in your kitchen have been <a href="https://theconversation.com/ode-to-the-fruit-fly-tiny-lab-subject-crucial-to-basic-research-38465">invaluable in biological research</a>. Biomedical scientists from all over the world study fruit flies to find <a href="https://doi.org/10.1016/S1369-7021(11)70113-4">causes and cures for diseases and genetic disorders</a>. And in <a href="https://faculty.fiu.edu/%7Etheobald/people/">our lab</a>, we study what the world looks like to insects, and how they use their vision to fly. This knowledge can inspire engineers to build better robots.</p>
<p>So, although it’s a nuisance to shoo flies away from your sandwich, maybe you can spare a few bits of your lunch?</p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/168549/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jamie Theobald receives funding from the National Science Foundation: IOS-1750833. </span></em></p><p class="fine-print"><em><span>Ravindra Palavalli-Nettimi does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A fly does some of its digesting outside its body before it even eats any food.Ravindra Palavalli-Nettimi, Postdoctoral Research Associate, Florida International UniversityJamie Theobald, Associate Professor of Biological Sciences, Florida International UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1614102021-05-24T21:17:52Z2021-05-24T21:17:52ZFly infertility shows we’re underestimating how badly climate change harms animals<figure><img src="https://images.theconversation.com/files/402285/original/file-20210524-19-85sqc1.jpg?ixlib=rb-1.1.0&rect=5%2C26%2C3589%2C2365&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Evidence of <a href="https://theconversation.com/male-fertility-how-everyday-chemicals-are-destroying-sperm-counts-in-humans-and-animals-158097">declining fertility</a> in humans and wildlife is growing. While chemicals in our environment have been identified as a major cause, our <a href="https://doi.org/10.1038/s41558-021-01047-0">new research</a> shows there’s another looming threat to animal fertility: climate change.</p>
<p>We know animals can die when temperatures rise to extremes they cannot endure. However, our research suggests males of some species can become infertile even at less extreme temperatures. </p>
<p>This means the distribution of species may be limited by the temperatures at which they can reproduce, rather than the temperatures at which they can survive. </p>
<p>These findings are important, because they mean we may be underestimating the impacts of climate change on animals – and failing to identify the species most likely to become extinct.</p>
<figure class="align-center ">
<img alt="two flies mating on a leaf" src="https://images.theconversation.com/files/402283/original/file-20210524-15-dbqptq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/402283/original/file-20210524-15-dbqptq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/402283/original/file-20210524-15-dbqptq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/402283/original/file-20210524-15-dbqptq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/402283/original/file-20210524-15-dbqptq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/402283/original/file-20210524-15-dbqptq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/402283/original/file-20210524-15-dbqptq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The distribution of some species may be limited by the temperatures at which they can reproduce.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Feeling the heat</h2>
<p>Researchers have known for some time that animal fertility is sensitive to heat stress.</p>
<p>For example, research shows a 2°C temperature rise dramatically reduces the production of sperm bundles and egg size <a href="https://www.cambridge.org/core/journals/zygote/article/abs/effect-of-elevated-temperature-on-fecundity-and-reproductive-timing-in-the-coral-acropora-digitifera/B9F5C799B513F46779792A8C88FA8466">in corals</a>. And in many <a href="https://theconversation.com/climate-change-effect-on-sperm-could-hold-key-to-species-extinction-107375">beetle</a> and <a href="https://www.nature.com/articles/s41893-020-0493-x">bee</a> species, fertilisation success drops sharply at high temperatures. </p>
<p>High temperatures have also been shown to affect fertilisation or sperm count in <a href="https://academic.oup.com/af/article/9/1/32/5167932">cows</a>, <a href="https://www.publish.csiro.au/rd/RD18159">pigs</a>, <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2012.02672.x">fish</a> and <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2017.2547">birds</a>.</p>
<p>However, temperatures that cause infertility have not been incorporated into predictions about how climate change will affect biodiversity. Our research aims to address this.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/male-fertility-how-everyday-chemicals-are-destroying-sperm-counts-in-humans-and-animals-158097">Male fertility: how everyday chemicals are destroying sperm counts in humans and animals</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="eggs on straw" src="https://images.theconversation.com/files/402272/original/file-20210524-15-1a2lm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/402272/original/file-20210524-15-1a2lm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/402272/original/file-20210524-15-1a2lm4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/402272/original/file-20210524-15-1a2lm4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/402272/original/file-20210524-15-1a2lm4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/402272/original/file-20210524-15-1a2lm4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/402272/original/file-20210524-15-1a2lm4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">High temperatures can affect bird reproduction.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>A focus on flies</h2>
<p>The paper <a href="https://doi.org/10.1038/s41558-021-01047-0">published today</a> involved researchers from the United Kingdom, Sweden and Australia, including one author of this article. The study examined 43 species of fly to test whether male fertility temperatures were a better predictor of global fly distributions than the temperatures at which the adult fly dies - also known as their “survival limit”.</p>
<p>The researchers exposed flies to four hours of heat stress at temperatures ranging from benign to lethal. From this data they estimated both the temperature that is lethal to 80% of individuals and the temperature at which 80% of surviving males become infertile.</p>
<p>They found 11 of 43 species experienced an 80% loss in fertility at cooler-than-lethal temperatures immediately following heat stress. Rather than fertility recovering over time, the impact of high temperatures was more pronounced seven days after exposure to heat stress. Using this delayed measure, 44% of species (19 out of 43) showed fertility loss at cooler-than-lethal temperatures. </p>
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<strong>
Read more:
<a href="https://theconversation.com/the-50-beautiful-australian-plants-at-greatest-risk-of-extinction-and-how-to-save-them-160362">The 50 beautiful Australian plants at greatest risk of extinction — and how to save them</a>
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</p>
<hr>
<p>The researchers then matched these findings to real-world data on the flies’ distribution, and estimated the average maximum air temperatures the species are likely to encounter in the wild. They found the distribution of fly species is linked more closely to the effects of high temperature on male fertility than on temperatures that kill flies.</p>
<p>These fertility responses are crucial to species survival. A separate study led by one author of this article, using simulated climate change in the laboratory, <a href="https://www.nature.com/articles/s41467-021-22546-w">showed</a> experimental populations of the same flies become extinct not because they can’t survive the heat, but because the males become infertile. Species from tropical rainforests were the first to succumb to extinction.</p>
<p>The prediction that tropical and sub-tropical species may be more vulnerable to climate change is <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/aen.12509">not new</a>. But the fertility findings suggest the negative impact of climate change may be even worse than anticipated.</p>
<figure class="align-center ">
<img alt="Flies on a stick" src="https://images.theconversation.com/files/402274/original/file-20210524-23-1dse916.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/402274/original/file-20210524-23-1dse916.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/402274/original/file-20210524-23-1dse916.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/402274/original/file-20210524-23-1dse916.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/402274/original/file-20210524-23-1dse916.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/402274/original/file-20210524-23-1dse916.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/402274/original/file-20210524-23-1dse916.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The research found fly fertility is affected at lower-than-lethal temperatures.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What does all this mean?</h2>
<p>Some animals have adapted to minimise the effect of high temperature on fertility. For instance, it’s thought testes in <a href="https://pubmed.ncbi.nlm.nih.gov/7153730/">male primates</a> and humans are externally located to protect the developing sperm from excessive heat.</p>
<p>As the planet warms, animals may further evolve to withstand the effects of heat on fertility. But the speed at which a species can adapt may be too slow to ensure their survival. Our research has shown both tropical and widespread species of flies <a href="https://www.nature.com/articles/s41467-021-22546-w">could not</a> increase their fertility when exposed to simulated global warming, even after 25 generations.</p>
<p>A study involving beetles <a href="https://www.nature.com/articles/s41467-018-07273-z">also indicates</a> fertility damage from successive heatwaves can accumulate over time. And more work is needed to determine how other stressors such as salinity, chemicals and poor nutrition may compound the fertility-temperature problem.</p>
<p>Whether our findings extrapolate to other species, including mammals such as humans, is not yet clear. It’s certainly possible, given evidence across the animal kingdom that fertility is sensitive to heat stress. </p>
<p>Either way, unless global warming is radically curbed, animal fertility will likely decline. This means Earth may be heading for far more species extinctions than previously anticipated.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-1-5-global-warming-limit-is-not-impossible-but-without-political-action-it-soon-will-be-159297">The 1.5℃ global warming limit is not impossible – but without political action it soon will be</a>
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</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/161410/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Belinda van Heerwaarden receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Ary Hoffmann receives funding from the Australian Research Council and the National Health and Medical Research Council.</span></em></p>New findings suggest the loss of fertility at high temperatures is a major threat to the survival of some species.Belinda van Heerwaarden, Future Fellow, The University of MelbourneAry Hoffmann, Professor, School of BioSciences and Bio21 Institute, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1578802021-05-04T20:05:53Z2021-05-04T20:05:53ZThese 3 tips will help you create a thriving pollinator-friendly garden this winter<figure><img src="https://images.theconversation.com/files/398524/original/file-20210504-21-1licsy5.jpg?ixlib=rb-1.1.0&rect=6%2C0%2C4477%2C3065&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The busy buzz of pollinating bees is a sound most of us associate with summer. If you live in temperate regions of Australia, you may start to notice fewer insects as the weather gets colder. Across most of the continent, however, some flower-visiting insects are active all year round – and some are more common in cooler months.</p>
<p>Planting winter-blooming flowers is a great way to support beneficial garden insects. Now is the perfect time to start planning your pollinator-friendly winter garden.</p>
<p>Flowers are an important source of food for insects such as bees, butterflies, wasps and hoverflies. Sugary nectar is an important source of carbohydrates, while pollen packs a powerful protein punch. </p>
<p>Planting flowers also attracts and sustains predatory insects. This can help keep pest species under control, meaning less need for <a href="https://theconversation.com/the-battle-against-bugs-its-time-to-end-chemical-warfare-111629">pesticides</a>. </p>
<figure class="align-center ">
<img alt="Rows of brassica plants" src="https://images.theconversation.com/files/398530/original/file-20210504-15-1mwen93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398530/original/file-20210504-15-1mwen93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398530/original/file-20210504-15-1mwen93.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398530/original/file-20210504-15-1mwen93.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398530/original/file-20210504-15-1mwen93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398530/original/file-20210504-15-1mwen93.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398530/original/file-20210504-15-1mwen93.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Planting flowers means less need for pesticides.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Know your winter-active insects</h2>
<p>First, let’s look at which pollinators and helpful predators you can expect in your garden in winter.
This guide, as well as the below gardening tips, applies primarily to <a href="https://www.abc.net.au/gardening/vegie-guide-zones/9796680">temperate</a> regions of Australia where temperatures become cool over winter. </p>
<p>The temperate region comprises the areas shown in blue below. It includes the coastal rim that curves from inland of Brisbane down to Sydney, Canberra, Melbourne and Adelaide, as well as Tasmania and the southwest tip of Western Australia. </p>
<figure class="align-center ">
<img alt="Australian climate zone map" src="https://images.theconversation.com/files/398570/original/file-20210504-23-11ypv07.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398570/original/file-20210504-23-11ypv07.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=414&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398570/original/file-20210504-23-11ypv07.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=414&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398570/original/file-20210504-23-11ypv07.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=414&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398570/original/file-20210504-23-11ypv07.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=520&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398570/original/file-20210504-23-11ypv07.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=520&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398570/original/file-20210504-23-11ypv07.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=520&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Australian climate zone map.</span>
<span class="attribution"><span class="source">Bureau of Meteorology</span></span>
</figcaption>
</figure>
<p>One of the most common pollinators is the Western honeybee (<em>Apis</em> <em>mellifera</em>). This introduced species evolved in cooler regions of the world and tends to be more cold-tolerant than most native bees. They’ll start to leave the hive when the temperature rises above 13°C, but are most active above 19°C. </p>
<p>Most native Australian bees prefer warmer temperatures. But a few species, such as reed bees (<em>Exonerua</em>) and the sugarbag bee (<em>Tetragonula carbonaria</em>), make an appearance on warmer winter days when the temperatures reach the mid- to high teens (although the sugar bag bee is usually not found south of Sydney).</p>
<p>Flies tend to be relatively tolerant of cooler temperatures, and are the stars of winter pollination. Hoverflies (Syrphidae), in particular, are garden <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/ps.5807?casa_token=7KogvY86YgEAAAAA%3A8lKPjQqyF3Sj_ZKtYcZa1xLEXZJrpk-oSDmh0sJD_obTSfubzj7__cazKa9qoFcI6oP8vB5eYxh9vJpF">superheroes</a>. </p>
<p>Adult hoverflies feed on nectar and pollen and can <a href="https://www.mdpi.com/2075-4450/11/6/341">pollinate</a> a range of plants. As a bonus, the maggot-like larvae of some hoverfly species are voracious <a href="https://www.youtube.com/watch?v=pW5TUsmVMLI">predators</a>, happily eating soft-bodied pests such as aphids. </p>
<hr>
<p>
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<strong>
Read more:
<a href="https://theconversation.com/its-bee-season-to-avoid-getting-stung-just-stay-calm-and-dont-swat-153625">It's bee season. To avoid getting stung, just stay calm and don't swat</a>
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</em>
</p>
<hr>
<figure class="align-center ">
<img alt="Hoverfly on plant" src="https://images.theconversation.com/files/398538/original/file-20210504-19-1f5mb8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398538/original/file-20210504-19-1f5mb8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398538/original/file-20210504-19-1f5mb8p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398538/original/file-20210504-19-1f5mb8p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398538/original/file-20210504-19-1f5mb8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398538/original/file-20210504-19-1f5mb8p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398538/original/file-20210504-19-1f5mb8p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hoverflies, which have similar patterning to bees, are common garden visitors in winter.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Hoverflies are often mistaken for bees or wasps because of their similar yellow and black patterning. The resemblance is not accidental; hoverflies have evolved to <a href="https://theconversation.com/to-bee-or-not-to-bee-why-some-insects-pretend-to-be-dangerous-65299">mimic</a> the appearance of stinging wasps and bees. Don’t let them fool you – hoverflies cannot sting and are generally harmless. </p>
<p>Some hoverfly species lay their eggs in stagnant water. The resulting larvae are known by the unflattering name “<a href="https://www.youtube.com/watch?v=k1vEarvsBx4">rat-tailed maggots</a>” because they breathe underwater through a long, thin siphon that resembles a tail. Don’t worry if you find these alien-looking critters swimming in your pond or beneath potted plants – the adults are flower-loving vegetarians that can help with pollination.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/hidden-women-of-history-eleanor-anne-ormerod-the-self-taught-agricultural-entomologist-who-tasted-a-live-newt-120158">Hidden women of history: Eleanor Anne Ormerod, the self taught agricultural entomologist who tasted a live newt</a>
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<hr>
<p>Other flies such as blowflies (Calliphoridae) are also active through the cooler months. Although blowflies are often considered pests, they play an important role in the <a href="https://www.mdpi.com/2075-4450/11/6/341/htm">pollination</a> of some fruits including avocado and mango, as well as seed production for carrot, celery and cauliflower. </p>
<p>With the right planting, you can also attract predators such as parasitoid wasps, lacewings and ladybird beetles. These insects mostly feed on other insects, but live longer and produce more offspring when they have access to a sweet sip of <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/eea.12668">nectar</a>. </p>
<p>So now we’ve met our winter pollinators and predators, read on for three ways to support them in your garden.</p>
<figure class="align-center ">
<img alt="blowfly on white flower" src="https://images.theconversation.com/files/398531/original/file-20210504-19-185dxez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398531/original/file-20210504-19-185dxez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398531/original/file-20210504-19-185dxez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398531/original/file-20210504-19-185dxez.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398531/original/file-20210504-19-185dxez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398531/original/file-20210504-19-185dxez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398531/original/file-20210504-19-185dxez.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Blowflies and other pollinating insects can be active in cooler months.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>1. Plant lots of flowers</h2>
<p>The easiest – and most beautiful – way to support winter insects is to plant lots of colourful winter-blooming flowers. Winter-loving brassicas such as broccoli, bok choi and mustard greens produce flowers that are a favourite food of many insects. Letting a few of these veggies go to flower will help support your local beneficial insects. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/398552/original/file-20210504-13-1blua2s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398552/original/file-20210504-13-1blua2s.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=332&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398552/original/file-20210504-13-1blua2s.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=332&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398552/original/file-20210504-13-1blua2s.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=332&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398552/original/file-20210504-13-1blua2s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=417&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398552/original/file-20210504-13-1blua2s.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=417&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398552/original/file-20210504-13-1blua2s.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=417&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Wes Mountain/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Salvias such as chia (<em>Salvia hispanica</em>) and basils such as sweet basil (<em>Ocimum basilicum</em>) will attract and support a variety of flower-visiting insects. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/398553/original/file-20210504-17-1lznz8g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398553/original/file-20210504-17-1lznz8g.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398553/original/file-20210504-17-1lznz8g.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398553/original/file-20210504-17-1lznz8g.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398553/original/file-20210504-17-1lznz8g.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398553/original/file-20210504-17-1lznz8g.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398553/original/file-20210504-17-1lznz8g.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=457&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Wes Mountain/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Native flowers such as coastal rosemary (<a href="https://www.anbg.gov.au/gnp/gnp1/westringia-fruticosa.html"><em>Westringia fruticosa</em></a>), <a href="http://anpsa.org.au/h-viol.html">Happy Wanderer</a> (<em>Hardenbergia violacea</em>), wattles (<em>Acacia</em>) and grevilleas are excellent for some of our pickier native insects.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/398554/original/file-20210504-15-12b34eu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398554/original/file-20210504-15-12b34eu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398554/original/file-20210504-15-12b34eu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398554/original/file-20210504-15-12b34eu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398554/original/file-20210504-15-12b34eu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398554/original/file-20210504-15-12b34eu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398554/original/file-20210504-15-12b34eu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Wes Mountain/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>2. Create variety</h2>
<p>When planning your winter garden, aim for a variety of colours, shapes and blooming times. Ideally, something should be in bloom all year round. Try to include as many native species as possible. Different winter-active insects have different preferences, so a variety of flower types can ensure you cater to a wider range of insects. </p>
<p>For example, a winter <a href="https://link.springer.com/article/10.1007/s11252-019-00914-1">survey</a> of community gardens in Sydney found honeybees were most abundant on sweet basil, lavender (<em>Lavendula</em>) and borage (<em>Borago officinalis</em>), while hoverflies (<em>Melangyna_sp) preferred Brassica rapa</em>, <em>Veronica persica</em> and <em>Stellaria media</em>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/398579/original/file-20210504-23-1cnsnjk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398579/original/file-20210504-23-1cnsnjk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398579/original/file-20210504-23-1cnsnjk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398579/original/file-20210504-23-1cnsnjk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398579/original/file-20210504-23-1cnsnjk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398579/original/file-20210504-23-1cnsnjk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398579/original/file-20210504-23-1cnsnjk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Wes Mountain/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The differences in flower preferences likely reflect differences in the shape and length of insect mouth parts. Honeybees have relatively long tongues that can access nectar in tube-shaped flowers (such as basil and lavender). </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/398581/original/file-20210504-15-6r33gf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398581/original/file-20210504-15-6r33gf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=336&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398581/original/file-20210504-15-6r33gf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=336&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398581/original/file-20210504-15-6r33gf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=336&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398581/original/file-20210504-15-6r33gf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398581/original/file-20210504-15-6r33gf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398581/original/file-20210504-15-6r33gf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">Wes Mountain/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Hoverflies, with their shorter tongues, have an easier time accessing nectar and pollen from shallower, daisy-like flowers. By planting a variety of flower shapes, you can make sure no insect misses out.</p>
<figure class="align-center ">
<img alt="Winter flowers in planter box" src="https://images.theconversation.com/files/398536/original/file-20210504-21-sfhelp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/398536/original/file-20210504-21-sfhelp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/398536/original/file-20210504-21-sfhelp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/398536/original/file-20210504-21-sfhelp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/398536/original/file-20210504-21-sfhelp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/398536/original/file-20210504-21-sfhelp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/398536/original/file-20210504-21-sfhelp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Plant flowers ina. variety of shapes, sizes and colours.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>3. Avoid insecticides</h2>
<p>Even organic or so-called “eco-friendly” insecticides may harm beneficial insects. Instead of insecticides, try low-impact options such as removing caterpillars by hand, or using a water spray to remove aphids.</p>
<p>If you feel you must use insecticides, read the label carefully and choose selective baits and sprays, which target one type of insect, over broad-spectrum sprays (such as pyrethrins, pyrethroids and neonicotinoids) which kill insects indiscriminately. Keep in mind that in some cases, using insecticides can actually make your pest problems worse by <a href="https://www.researchgate.net/publication/227125142_A_Review_of_Resurgence_and_Replacement_Causing_Pest_Outbreaks_in_IPM">killing beneficial predatory insects</a>.</p>
<h2>Get planting!</h2>
<p>Planting a garden for winter-active insects is a wonderful way to support local wildlife. Your garden will thrive as a result of the free pollination and pest control services these beneficial insects provide. </p>
<p>So get planting, and enjoy the delight of a buzzing garden full of helpful insects.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-tiny-ants-have-invaded-your-house-and-what-to-do-about-it-132092">Why tiny ants have invaded your house, and what to do about it</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/157880/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tanya Latty receives funding from the Australian Research Council, the Herman Slade Foundation and Agrifutures Australia. She has previously received funding from the City of Sydney and the Branco Weiss Society in Science Fellowship. She is vice president of the Australian Society for the Study of Animal Behaviour and convener for the education committee of the Australian Entomological Society.
</span></em></p>Planting a garden for winter-active insects is a wonderful way to support local biodiversity. Your garden will thrive with the free pollination and pest control services the insects provide.Tanya Latty, Associate professor, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1516722021-03-01T13:16:26Z2021-03-01T13:16:26ZWhy do flowers smell?<figure><img src="https://images.theconversation.com/files/376865/original/file-20201231-17-b5tlb0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A floral scent can be enjoyable for a person, but it has an important job for the flower.</span> <span class="attribution"><span class="source">Richard L. Harkess</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>Why do flowers smell? – Henry E., Age 9, Somerville, Massachusetts</strong></p>
</blockquote>
<hr>
<p>Imagine walking through a tropical forest as a sweet scent wafts through the air. A little farther down the path, the putrid stench of rotting flesh makes you catch your breath. Upon investigation, you find that both odors originate from flowers – but why do flowers smell like anything at all?</p>
<p>It’s actually part of a strategy that helps flowering plants reproduce themselves and spread their species. Certain scents help these flowers solve a big problem.</p>
<p>Plants flower to produce seeds that can go on to become new plants. To make a viable seed, pollen from one part of the flower must <a href="https://www.fs.fed.us/wildflowers/pollinators/What_is_Pollination/">fertilize the ovules</a> in another part of the flower. <a href="https://www.fs.fed.us/wildflowers/pollinators/What_is_Pollination/birdsandbees.shtml">Some plants can self-pollinate</a>, using their own pollen to fertilize the ovule. Others require pollen from another plant of the same species – that’s called <a href="https://www.fs.fed.us/wildflowers/pollinators/What_is_Pollination/birdsandbees.shtml">cross-pollination</a>.</p>
<p>So how does one plant get some other individual plant’s pollen where it needs to be?</p>
<p>Sometimes gravity helps pollen fall into place. Sometimes wind carries it. Wind-pollinated flowers, like those of many trees and grasses, don’t produce a scent.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/382302/original/file-20210203-21-1afen3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bee transfers pollen from one blossom to another" src="https://images.theconversation.com/files/382302/original/file-20210203-21-1afen3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382302/original/file-20210203-21-1afen3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382302/original/file-20210203-21-1afen3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382302/original/file-20210203-21-1afen3g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382302/original/file-20210203-21-1afen3g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382302/original/file-20210203-21-1afen3g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382302/original/file-20210203-21-1afen3g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Animal pollinators can carry pollen from one flower’s stigma to another flower’s ovule as they forage for food.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/the-process-of-cross-pollination-with-bee-royalty-free-illustration/1060121100">ttsz/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Other flowers are pollinated by birds, bats, insects or even small rodents carrying the pollen from one flower to another. In these cases, the flowers might provide a little incentive. <a href="https://www.esa.org/blog/2018/04/04/vertebrate-polinator-metaanalysis/">Animal pollinators are rewarded</a> by sweet energy- and nutrient-rich nectar or protein-packed pollen they can eat.</p>
<p>Flowers that need the help of insects and bats go one step further, producing a floral scent that acts as a smelly kind of welcome sign for just the right pollinator.</p>
<p>An orchid blooming in the tropical forest or a rose in your garden needs to attract a pollinator to bring pollen from flowers of the same species. However, there are flowers which look similar but are from other species. To differentiate itself from other flowers, each species’ flowers puts out a unique scent to attract specific pollinators.</p>
<p>Similar to the perfumes at a department store counter, flower scents are made up from a large and diverse number of chemicals which evaporate easily and float through the air. The type of chemical, its amount and its interaction with other chemicals give the flower its unique scent. The <a href="https://www.smithsonianmag.com/smart-news/why-do-flowers-smell-good-349826/">scent of a rose</a> may consist of as many as 400 different chemicals.</p>
<p>People can smell these floral scents because they easily evaporate from the flower, drifting on the air currents to attract pollinators. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/382303/original/file-20210203-21-8gnlyv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="corpse flower blossom in a greenhouse" src="https://images.theconversation.com/files/382303/original/file-20210203-21-8gnlyv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382303/original/file-20210203-21-8gnlyv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382303/original/file-20210203-21-8gnlyv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382303/original/file-20210203-21-8gnlyv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382303/original/file-20210203-21-8gnlyv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382303/original/file-20210203-21-8gnlyv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382303/original/file-20210203-21-8gnlyv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The giant corpse flower has a very stinky scent that its pollinators love.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/titan-arum-royalty-free-image/911610946">Photography by Mangiwau/Moment via Getty Images</a></span>
</figcaption>
</figure>
<p>Flower fragrances may be sweet and fruity, or they can be musky, even stinky or putrid depending on the pollinator they are trying to attract. A blooming apple or cherry tree emits a sweet scent to attract bumblebees, honeybees and other bees. But stick your nose into the beautiful flowers of a pear tree – a close relative of apples and cherries – and you may recoil in disgust, as these flowers smell musky or putrid to attract flies as pollinators. Similarly, the <a href="https://www.usbg.gov/corpse-flowers-us-botanic-garden">corpse flower</a>, native to Indonesian rainforests, emits a foul odor reminiscent of rotting flesh to attract flies and beetles to pollinate its flowers.</p>
<p>Moths and bats flying at night locate flowers by the scent some release after the Sun goes down. The night-blooming cereus, the saguaro cactus and the dragon fruit all have large white flowers which open at night – they seem to glow in the moonlight, making them visible to nocturnal visitors. Their strong perfume helps guide pollinators inside. While drinking the sweet nectar, the pollinator picks up pollen which it then deposits in the next flower visited.</p>
<p>Once pollinated, the flower stops producing a floral scent and nectar and redirects its energy to the fertilized embryo that will become the seed.</p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
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<p class="fine-print"><em><span>Richard Harkess has received funding from USDA/NIFA. </span></em></p>Not all flowers smell good, to people at least, but their scents are a way to attract pollinators.Richard L. Harkess, Professor of Floriculture and Ornamental Horticulture, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1543342021-02-10T13:14:11Z2021-02-10T13:14:11ZTiny cacao flowers and fickle midges are part of a pollination puzzle that limits chocolate production<figure><img src="https://images.theconversation.com/files/382043/original/file-20210202-23-1me4d8a.jpg?ixlib=rb-1.1.0&rect=18%2C9%2C6211%2C4138&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Only 10%-20% of cacao flowers are pollinated.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/chocolate-bar-cocoa-powder-cocoa-beans-and-cocoa-royalty-free-image/1193489803">carlosgaw/E+ via Getty Images</a></span></figcaption></figure><p>It’s almost impossible to imagine a world without chocolate. Yet cacao trees, which are the source of chocolate, are vulnerable. </p>
<p>I am a passionate chocolate lover <a href="https://scholar.google.com/citations?hl=en&user=qvmWZYwAAAAJ">and an entomologist</a> who studies cacao pollination. The crop’s sustainability currently appears to depend on several species of tiny fly pollinators, who are frankly struggling to get the job done. </p>
<h2>Thousands of flowers</h2>
<p>Chocolate is derived from the seeds of the cacao tree, <em>Theobroma cacao L.</em>, which literally means “food of the gods.” The plant <a href="https://doi.org/10.1038/s42003-018-0168-6">originated in the Western Amazon region of South America</a> and has been cultivated for more than 3,000 years in many parts of Central and South America. Today it’s grown in equatorial regions around the world, including western Africa and several tropical regions in Asia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Trunk and branches of cacao tree covered in tiny flowers." src="https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382052/original/file-20210202-17-1xya6ws.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cacao blossoms are unusual for a tree.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cacao-flowers-on-tree-royalty-free-image/1137440314">dimarik/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>A mature cacao tree can produce many thousands of flowers each year. These flowers are tiny, only a half inch or so in diameter (1-2 cm). The flowers typically grow in clusters <a href="https://upf.com/book.asp?id=9780813030449">directly from the trunk of the tree or off large branches</a>. </p>
<figure class="align-right ">
<img alt="Close-up of cacao pod on a tree." src="https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382057/original/file-20210202-15-fkjd00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Pods can be green, white, yellow, purplish or red in color.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-cacao-fruit-on-tree-royalty-free-image/1205928514">Neilstha Firman/EyeEm via Getty Images</a></span>
</figcaption>
</figure>
<p>Each flower requires pollination to successfully produce a nearly football-sized fruit – a pod containing 30-60 seeds, which can be processed to make chocolate. </p>
<p>It sounds straightforward but, in fact, successful <a href="https://doi.org/10.1016/j.ppees.2010.02.005">cacao pollination is problematic</a> in many regions. Only around 10%-20% of the flowers produced by a cacao tree are successfully pollinated. The rest, <a href="https://doi.org/10.1016/j.agee.2017.05.021">up to 90%, never receive pollen</a> – or do not receive enough pollen to create fruits.</p>
<p>Scientists don’t fully understand cacao pollination, which is surprising given that over 50 million people worldwide currently <a href="https://www.iisd.org/ssi/commodities/cocoa-coverage/">depend on chocolate for their livelihood</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A midge on human skin." src="https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382532/original/file-20210204-22-1dkpkg7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">In the U.S., some midges are better known as ‘no-see-ums.’</span>
<span class="attribution"><a class="source" href="https://eol.org/media/7472715">tompiast</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>A big job for a tiny fly</h2>
<p>The insects responsible for pollinating cacao’s tiny flowers are, themselves, also tiny, in order to access the flower’s reproductive structures. <a href="https://doi.org/10.1016/j.agee.2017.05.021">Biting midges from the <em>Ceratopogonidae</em> family and gall midges from the <em>Cecidomyiidae</em> family</a> are among the most important known cacao pollinators worldwide. </p>
<p>The majority of cacao trees are what are known as <a href="https://doi.org/10.1093/jxb/erx293">self-incompatible</a>, meaning they cannot pollinate themselves. Successful pollinators must pick up pollen from the male parts of a flower of one tree and deposit it on the female parts of a flower on another tree. </p>
<p>Cacao flowers are also short-lived, typically receptive to pollen for only one or two days. Flowers that do not receive ample pollen <a href="https://doi.org/10.1016/j.agee.2017.05.021">die and fall within 36 hours</a> of opening.</p>
<p>Evidence suggests <a href="https://doi.org/10.1002/eap.1491">improving midge habitat</a> can increase fruit yield. So, in some cacao-growing areas, current farming practices include developing and maintaining suitable ground habitat within and near cacao orchards in an effort to increase the number of midges capable of pollen transmission.</p>
<h2>Lingering mysteries</h2>
<p>The <a href="https://doi.org/10.21273/HORTSCI12852-18">success of artificial or hand pollination</a>, which can more than double yields, shows cacao trees are capable of producing many more pods than they currently do.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/lXe-xptz2Nk?wmode=transparent&start=272" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Workers at a cacao farm in Ghana demonstrate how they hand-pollinate the tree’s flowers.</span></figcaption>
</figure>
<p>It’s hard not to wonder: Why aren’t midges doing a better job of pollinating cacao flowers? Scientists think part of the answer might be that midges <a href="https://doi.org/10.1007/s10886-019-01118-9">don’t solely depend upon cacao flowers for their life cycle</a>. Because they can get sugar from other plant sources, they are likely passive rather than active pollinators of cacao. Scientists also wonder if they are up to the task of flying the significant distances between wild trees.</p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>All of which begs the question: Are there insects better designed for the job? And, if so, where did they go?</p>
<p>Most studies linking midges to cacao pollination were conducted in orchards, while the biology of wild cacao pollination is almost completely unstudied. </p>
<p>One exception is a study that looked at <a href="https://doi.org/10.1007/s10457-016-0019-8">both cultivated and wild cacao in Bolivia</a>. It found that midges represented only 2% of all insect visitors to wild trees. Other flies and tiny wasps were more common there. </p>
<p>These results are intriguing and raise the possibility that one or more unknown insects are the primary pollinators of cacao in the wild. Only additional study of wild cacao may reveal if this is the case. Such information could have far-reaching implications for the chocolate industry.</p><img src="https://counter.theconversation.com/content/154334/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>DeWayne Shoemaker works for the University of Tennessee Institute of Agriculture</span></em></p>Entomologists wonder if the insects currently pollinating farmed cacao are the right ones for the task.DeWayne Shoemaker, Professor and Department Head, Entomology and Plant Pathology, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1536732021-01-21T14:32:20Z2021-01-21T14:32:20ZPollinators: neonicotinoid pesticides stop bees and flies from getting a good night’s sleep<figure><img src="https://images.theconversation.com/files/379975/original/file-20210121-17-1pzg39p.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3543%2C2386&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sleeping on the job?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/focus-stacking-bufftailed-bumblebee-dumbledor-dumbledore-636775153">Maciej Olszewski/Shutterstock</a></span></figcaption></figure><p>Neonicotinoids, the most commonly used pesticides in the world, were <a href="https://www.theguardian.com/environment/2018/apr/27/eu-agrees-total-ban-on-bee-harming-pesticides">banned in the EU</a> in 2018. More than <a href="https://petition.parliament.uk/archived/petitions/104796">99,000 people</a> petitioned the UK government to support the ban amid a wealth of scientific evidence linking this group of chemicals to poor health in bees, from the reduced production of <a href="https://science.sciencemag.org/content/336/6079/351">bumblebee queens</a> to <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2016.0506">slashed sperm counts</a> among male honeybees.</p>
<p>The UK government had <a href="https://www.theguardian.com/environment/2017/nov/09/the-evidence-points-in-one-direction-we-must-ban-neonicotinoids">pledged</a> to keep the EU’s restrictions post-Brexit, but recently <a href="https://www.gov.uk/government/publications/neonicotinoid-product-as-seed-treatment-for-sugar-beet-emergency-authorisation-application/statement-on-the-decision-to-issue-with-strict-conditions-emergency-authorisation-to-use-a-product-containing-a-neonicotinoid-to-treat-sugar-beet">granted a special exemption</a> to allow farmers to use the neonicotinoid thiamethoxam on sugarbeet throughout 2021, and possibly until 2023.</p>
<p>If this signals the government’s intention to roll back regulations on agricultural chemicals now that the UK has left the EU, the consequences for pollinating insects could be dire. Research into the effects of these pesticides on pollinators is still ongoing, but new harmful effects are discovered all the time.</p>
<figure class="align-center ">
<img alt="A tractor sprays chemicals onto a vegetable field at dusk." src="https://images.theconversation.com/files/379966/original/file-20210121-19-gkw885.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/379966/original/file-20210121-19-gkw885.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379966/original/file-20210121-19-gkw885.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379966/original/file-20210121-19-gkw885.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379966/original/file-20210121-19-gkw885.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379966/original/file-20210121-19-gkw885.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379966/original/file-20210121-19-gkw885.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Neonicotinoids are sprayed onto farm fields to control pests such as aphids and grubs.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tractor-spraying-pesticides-on-vegetable-field-664124608">Fotokostic/Shutterstock</a></span>
</figcaption>
</figure>
<p>In <a href="https://www.nature.com/articles/s41598-021-81548-2">a new study</a>, my colleagues and I have uncovered the most recent example. We looked into the effect of these pesticides on the body clock and sleep of flies and bumblebees. Just like us, insects need sleep. And, like us, they have an internal sense of time – more commonly known as a body clock – which helps them synchronise their activity and sleep patterns with the rest of the world. Your body clock might allow you to wake up just a few minutes before your alarm goes off. For insects, it ensures they’re able to forage in the day when flowers are open and sleep at night when it’s usually too dark to fly.</p>
<p>Using lab-based colonies of buff-tailed bumblebees, the <a href="https://www.bumblebeeconservation.org/white-tailed-bumblebees/buff-tailed-bumblebee/">most common British bumblebee species</a>, we showed that a neonicotinoid pesticide called imidacloprid turns night into day for bees. Foraging bumblebees were fed concentrations of imidacloprid that were similar to what they might encounter in the wild (around ten parts per billion). After exposure, the dosed bees were more likely to try to forage at nighttime and sleep in the daytime, and they were more sluggish overall, going on far fewer foraging trips than normal.</p>
<p>At the same time as we were experimenting on bumblebees, we were also studying the response of fruit flies to neonicotinoids. Scientists often use fruit flies as a model to help understand other animals, as we have a deep understanding of their genes and the ability to edit them. In our study, we labelled the brain cells which set the pace of the fruit fly body clock with fluorescent dye, to see if the pesticides could be directly affecting them. </p>
<figure class="align-center ">
<img alt="A fruit fly on a piece of food." src="https://images.theconversation.com/files/379972/original/file-20210121-15-1xfl9dj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/379972/original/file-20210121-15-1xfl9dj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/379972/original/file-20210121-15-1xfl9dj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/379972/original/file-20210121-15-1xfl9dj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/379972/original/file-20210121-15-1xfl9dj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/379972/original/file-20210121-15-1xfl9dj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/379972/original/file-20210121-15-1xfl9dj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Fruit flies are useful for studying how chemicals affect the brain.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fruit-fly-drosophilidae-682007272">Ant Cooper/Shutterstock</a></span>
</figcaption>
</figure>
<p>In a normal fly, these cells collect information from the eyes and other light-sensing organs. The cells then change shape between daytime and nighttime and release signals to other parts of the body to ensure that sleep and other activities happen at the right time of day. But neonicotinoids appeared to interfere with both of these processes, freezing the body clock cells in daytime mode. Given how similar these cells are between fruit flies and bees, this process may be behind the effects on sleep and foraging that we saw in bumblebees.</p>
<h2>The environmental impact</h2>
<p>If bees can’t synchronise their foraging with the dawn, when nectar and pollen are most abundant, this will limit the amount of food they can gather, stunting the colony’s ability to grow and produce more bees. </p>
<p>The body clock is also an important part of communication in bees. Honeybees have a <a href="https://theconversation.com/follow-the-bees-dance-to-find-landscapes-green-hotspots-27004">dance language</a> which lets them tell each other where the best flowers are. They use the position of the sun in the sky as a tool for navigation, which means that honeybees need to be able to keep track of the time of day within the darkness of the hive. If their body clock is disrupted, it could affect their ability to communicate vital information to each other and reduce their ability to forage and pollinate.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-discovered-more-about-the-honeybee-wake-up-call-and-it-could-help-save-them-105751">We discovered more about the honeybee 'wake-up call' — and it could help save them</a>
</strong>
</em>
</p>
<hr>
<p>The changes to sleep that we saw in the buff-tailed bumblebees are also worrying. Sleep during the night helps <a href="https://jeb.biologists.org/content/215/22/3981">bees form memories</a>, and so if neonicotinoids are disrupting their sleep, it could cause problems with remembering important information, such as the route back to the hive. The correct timing of sleep is also really important for childcare in the colony. When bumblebees are looking after their young, they have to tend to them and feed them round the clock, taking little naps between feeds. If neonicotinoids change their sleep patterns in a way that they can’t control, adult bumblebees may struggle to properly care for the next generation. All of these effects could potentially prevent colonies from growing and reproducing properly, threatening their long-term survival.</p>
<p>Bumblebees, like honeybees and other bees, are important pollinators for <a href="https://repository.rothamsted.ac.uk/item/8704y/the-dependence-of-crop-production-within-the-european-union-on-pollination-by-honey-be">84% of crops</a> and <a href="https://www.cbd.int/agro/peer_review_pollinators.pdf">80% of wild flowering plants</a> in Europe. Neonicotinoids pose a real threat to not only the health of these pollinating insects, but the agriculture and ecosystems they support. As a scientist who studies the effects of these chemicals, I hope that the “emergency use” that was recently granted by the UK government isn’t a sign of worse things to come.</p><img src="https://counter.theconversation.com/content/153673/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kiah Tasman receives funding from BBSRC. </span></em></p>Chemicals banned in the EU were recently granted an exemption for limited use in the UK.Kiah Tasman, Teaching Associate in Physiology, Pharmacology and Neuroscience, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1487222020-12-28T21:42:20Z2020-12-28T21:42:20ZBzzz, slap! How to treat insect bites (home remedies included)<figure><img src="https://images.theconversation.com/files/373750/original/file-20201209-17-7qzomc.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C1000%2C657&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/protecting-mosquito-on-camping-by-river-1485041048">Shutterstock</a></span></figcaption></figure><p>It’s the holidays and we’re spending more time outdoors. This means we’re exposed to the more annoying and painful aspects of summer — insect bites and stings. </p>
<p>There are plenty of products at the local pharmacy to treat these. Some treat the initial bite or sting, others the itchy aftermath.</p>
<p>What about natural remedies? Few studies have actually examined them. But if they work for you, and don’t irritate already inflamed skin, there’s likely no harm in continuing.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/buzz-buzz-slap-why-flies-can-be-so-annoying-52296">Buzz, buzz, slap! Why flies can be so annoying</a>
</strong>
</em>
</p>
<hr>
<h2>Why do insects bite and sting?</h2>
<p>When insects bite and sting, they are either defending themselves or need something from us (like blood).</p>
<p>Whatever the motivation, it can leave us with a painful or itchy reaction, sometimes a severe allergic reaction, or even a debilitating disease.</p>
<p>While insects sometimes get a bad rap, there are relatively few that actually pose a serious threat to our health.</p>
<p><strong>Flies, mosquitoes</strong></p>
<p>Many types of flies, especially mosquitoes, bite. In most instances, they need blood for nutrition or the development of eggs. The method of “biting” can vary between the different types of flies. While mosquitoes inject a needle-like tube to suck our blood, others chew or rasp away at our skin.</p>
<p>While researchers have studied what happens when <a href="https://journals.lww.com/itch/Fulltext/2019/03000/Beat_the_bite__pathophysiology_and_management_of.1.aspx">mosquitoes bite</a>, there is still much to learn about how to treat the bites.</p>
<p>So, avoiding mosquito bites is especially important given some can <a href="https://theconversation.com/explainer-what-is-ross-river-virus-24630">transmit pathogens that make us sick</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/feel-like-youre-a-mozzie-magnet-its-true-mosquitoes-prefer-to-bite-some-people-over-others-128788">Feel like you're a mozzie magnet? It's true – mosquitoes prefer to bite some people over others</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/372798/original/file-20201203-15-1hz7tea.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/372798/original/file-20201203-15-1hz7tea.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/372798/original/file-20201203-15-1hz7tea.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/372798/original/file-20201203-15-1hz7tea.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/372798/original/file-20201203-15-1hz7tea.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/372798/original/file-20201203-15-1hz7tea.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/372798/original/file-20201203-15-1hz7tea.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We still have lots to learn about treating mosquito bites.</span>
<span class="attribution"><span class="source">A/Prof Cameron Webb</span></span>
</figcaption>
</figure>
<p><strong>Fleas, lice, mites and ticks</strong></p>
<p>There are lots of other insects (such as bed bugs, fleas, lice) and other arthropods (such as mites, ticks) <a href="https://healthinfonet.ecu.edu.au/key-resources/resources/30905/?title=Arthropod%20pests%20of%20public%20health%20significance%20in%20Australia">that bite</a>. </p>
<p>But it is difficult to determine which insect has bitten us <a href="https://www.mdpi.com/2075-4418/10/5/308/htm">based on the bite reaction alone</a>. This is generally because different people react in different ways to the <a href="https://theconversation.com/curious-kids-when-we-get-bitten-by-a-mosquito-why-does-it-itch-so-much-93347">saliva injected</a> as they start to suck our blood.</p>
<p><strong>Bees, wasps, ants</strong></p>
<p>Then there are stinging insects, such as bees, wasps and ants. These are typically just defending themselves.</p>
<p>But as well as being painful, the venom they inject when they sting can cause <a href="https://www.allergy.org.au/patients/insect-allergy-bites-and-stings/allergic-reactions-to-bites-and-stings">potentially severe allergic reactions</a>.</p>
<h2>How do you best treat a sting or bite?</h2>
<p>If you suffer potentially severe allergic reactions from <a href="https://www.sciencedirect.com/science/article/abs/pii/S1081120610612598">bites or stings</a>, immediately seek appropriate medical treatment. But for many other people, it is the initial painful reaction and itchy aftermath that require attention.</p>
<p>Despite how common insect bites can be, there is <a href="https://www.bmj.com/content/370/bmj.m2856">surprisingly little formal research</a> into how best to treat them. Most of the research is focused on insect-borne diseases.</p>
<p>Even for recommended treatments, <a href="https://dtb.bmj.com/content/50/4/45.abstract">there is little evidence</a> they actually work. Instead, recommendations are based on expert opinion and clinical experience.</p>
<p>For instance, heath authorities promote <a href="https://www.healthdirect.gov.au/insect-bites-and-stings">some general advice</a> on treating insect bites and stings. This includes using pain relief medication (such as paracetamol or ibuprofen). They also advise applying a cold compress (such as a cold pack, ice, or damp cloth soaked in cold water) to the site of the sting or bite to help reduce the inflammation and to ease some of the discomfort.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/373745/original/file-20201209-15-v7t8cg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Refreshing red drink in glass with ice cubes and lemon" src="https://images.theconversation.com/files/373745/original/file-20201209-15-v7t8cg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/373745/original/file-20201209-15-v7t8cg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/373745/original/file-20201209-15-v7t8cg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/373745/original/file-20201209-15-v7t8cg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/373745/original/file-20201209-15-v7t8cg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/373745/original/file-20201209-15-v7t8cg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/373745/original/file-20201209-15-v7t8cg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ice cubes aren’t just for summer cocktails. They can help reduce inflammation from insect bites and stings.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/top-view-spritz-aperitif-aperol-cocktail-279703073">Shutterstock</a></span>
</figcaption>
</figure>
<p>There is also specific advice for <a href="https://www.allergy.org.au/patients/insect-allergy-bites-and-stings/allergic-reactions-to-bites-and-stings">dealing with stings</a> and removing <a href="https://theconversation.com/tackling-the-tricky-task-of-tick-removal-26306">ticks</a>.</p>
<p>However, if you do nothing, the discomfort of the bite or sting will eventually fade after a few days. The body quickly recovers, just as it would for a cut or bruise.</p>
<p>If you’re still in pain for more than a couple of days, or there are signs of an allergic reaction, seek medical assistance.</p>
<h2>What about the itch?</h2>
<p>Once the initial pain has started to fade, the itch starts. That’s because the body is reacting to the <a href="https://www.frontiersin.org/articles/10.3389/fcimb.2020.00407/full">saliva injected</a> when insects bite.</p>
<p>For many people, this is incredibly frustrating and it is all too easy to get trapped in a cycle of itching and scratching.</p>
<p>In some cases, medications, such as <a href="https://www.healthdirect.gov.au/medicines/brand/amt,1159191000168108/hydrocortisone-pharmacy-action">corticosteroid</a> creams or <a href="https://emj.bmj.com/content/23/9/721.2">antihistamines</a> could help alleviate the itchiness. You can buy these from the pharmacy.</p>
<p>Then there’s <a href="https://www.healthline.com/health/calamine-lotion-uses">calamine lotion</a>, a mainstay in many Australian homes used to treat the itchiness caused by insect bites. But there are <a href="https://www.sciencedirect.com/science/article/pii/S1080603206702757">few studies</a> that demonstrate it works.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/are-itchier-insect-bites-more-likely-to-make-us-sick-61422">Are itchier insect bites more likely to make us sick?</a>
</strong>
</em>
</p>
<hr>
<h2>Do any home remedies work?</h2>
<p>If you’re looking for a home remedy to treat insect bites and the itchiness that comes with it, a quick internet search will keep you busy for days. </p>
<p><a href="https://www.healthline.com/health/outdoor-health/home-remedies-for-mosquito-bites">Potential home remedies</a> include: tea bags, banana, tea tree or other essential oils, a paste of baking soda, vinegar, aloe vera, oatmeal, honey and even onion.</p>
<p>There is little evidence any of these work. But not many have actually been scientifically evaluated. </p>
<p>Tea tree oil is one of the few. While it is said to help <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-4632.2012.05654.x">treat skin reactions</a>, the oil itself can cause skin reactions <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/cod.12591">if not used as directed</a>.</p>
<p>However, if a home remedy works for you, and it’s not causing additional irritation, there’s no harm in using it if you’re getting some relief. </p>
<p>With so much uncertainty about how to treat insect bites and stings, perhaps it is best if we avoid exposure in the first place. There are <a href="https://theconversation.com/the-best-and-worst-ways-to-beat-mosquito-bites-70274">plenty of insect repellents</a> available at your local pharmacy or supermarket that do this safely and effectively.</p><img src="https://counter.theconversation.com/content/148722/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on mosquito biology. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management.</span></em></p>Summer can bring out the bugs. Here’s what to do if you miss a spot when applying insect repellent.Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1478152020-10-09T22:13:41Z2020-10-09T22:13:41ZMike Pence’s fly: From Renaissance portraits to Salvador Dalí, artists used flies to make a point about appearances<figure><img src="https://images.theconversation.com/files/362781/original/file-20201009-17-q4wkxh.jpg?ixlib=rb-1.1.0&rect=2%2C0%2C1623%2C764&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">'Portrait of a Woman of the Hofer Family,' Swabian artist, c. 1470, and a picture showing a fly on U.S. Vice-President Mike Pence during the Oct. 7 debate at University of Utah in Salt Lake City.</span> <span class="attribution"><span class="source">(Wikimedia Commons/AP Photo/Julio Cortez) </span></span></figcaption></figure><p>After this week’s vice-presidential debate in the United States, <a href="https://www.youtube.com/watch?v=EwVRqKhM9Gg">the fly that landed on Vice-President Mike Pence’s</a> head <a href="https://www.bbc.com/news/election-us-2020-54459544">was more of a sensation than the details of the debate</a> — at least on social media.
The fly has already been immortalized as a <a href="https://store.joebiden.com/truth-over-flies-fly-swatter/">Biden/Harris fly swatter</a> <a href="https://www.usatoday.com/story/money/2020/10/08/fly-pence-head-vp-debate-biden-harris-campaign-fly-swatters/5927281002/">(sorry, they’re all sold out)</a> and sparked <a href="https://people.com/style/the-fly-that-landed-on-mike-pences-head-during-the-vp-debate-is-now-a-halloween-costume/">a Halloween costume</a>. </p>
<p>In many circumstances, flies are unremarkable. That’s probably why a <a href="https://www.lexico.com/definition/mouchard">French word for spy</a> is connected to the same word <a href="https://www.collinsdictionary.com/dictionary/french-english/mouche">for fly, <em>mouche</em></a>. When a fly becomes famous, it’s worth wondering why. </p>
<p>Flies have long held <a href="https://www.academia.edu/28237822/Catching_an_Absent_Fly">symbolic meaning in the history of art</a>. In portraits made in Renaissance Europe, the presence of a fly symbolizes the transience of human life (buzzbuzzpfft!). In the great scheme of things, our lives are no longer than that of a fly. For me as an art historian, the fly was a moment to reflect not only on the history of flies in western painting, but to begin considering what the long <a href="https://www.washingtonpost.com/lifestyle/style/life-imitates-art-and-so-a-fly-landed-on-mike-pences-head/2020/10/08/07bb328e-0918-11eb-9be6-cf25fb429f1a_story.html">history of this symbolism</a> may reveal about why the fly generated so much buzz. </p>
<h2>Humility, impermanence, illusion</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/362731/original/file-20201009-15-9syegv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Renaissance Portrait of a woman with a fly on her head." src="https://images.theconversation.com/files/362731/original/file-20201009-15-9syegv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/362731/original/file-20201009-15-9syegv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=798&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362731/original/file-20201009-15-9syegv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=798&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362731/original/file-20201009-15-9syegv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=798&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362731/original/file-20201009-15-9syegv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1003&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362731/original/file-20201009-15-9syegv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1003&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362731/original/file-20201009-15-9syegv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1003&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">‘Portrait of a Woman of the Hofer Family,’ c. 1470, by an artist from the German (Swabian) School.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:German_(Swabian)_School_-_Portrait_of_a_Woman_of_the_Hofer_Family_-_NG722_-_National_Gallery.jpg">(Wikimedia Commons)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Take, for example, an extraordinary little painting known today as <em><a href="https://www.nationalgallery.org.uk/paintings/swabian-portrait-of-a-woman-of-the-hofer-family">Portrait of a Woman of the Hofer Family</a></em>, painted in about 1470 by an artist from the German (Swabian) School, now <a href="https://www.artuk.org/discover/artworks/portrait-of-a-woman-of-the-hofer-family-114961">in the National Gallery in London</a>. Her elaborate white head covering highlights a perfect little fly, that’s settled on her just to remind us <a href="https://www.artsy.net/article/artsy-editorial-lush-17th-century-paintings-striking-reminders-mortality">that our life, like hers, is impermanent</a>. </p>
<p>The corollary is that we’re supposed to do the best we can with the time we’ve got. When it comes to time and eternity, <a href="https://poets.org/poem/fly">as painter and poet William Blake wrote</a>: “Am not I / A fly like thee? / Or art not thou / A man like me?” The fly is a little reminder of humility. </p>
<p>Painters could also include a fly to draw attention to themselves, demonstrating with their “<a href="https://web.archive.org/web/20040928002941/http://www.nga.gov/press/2002/exhibitions/deceptions/walltxt.shtm">trompe-l’oeil</a>” (deceiving the eye) tricks that they could paint in a manner that seemed so real, a viewer of the portrait would be tempted to try to swat the fly away. The 16th-century Italian painter <a href="https://www.britannica.com/biography/Giorgio-Vasari">Giorgio Vasari, biographer of Italian Renaissance artists</a>, tells a story about the <a href="https://global.oup.com/academic/product/the-lives-of-the-artists-9780199537198?cc=ca&lang=en&">painter Giotto fooling his teacher Cimabue</a> by adding a realistic-looking fly to a painting. </p>
<p>Salvador Dalí, who was pretty much the lord of the flies (<a href="https://doi.org/10.1093/ae/59.1.28">he painted them a lot</a>) included a fly on the watch face of his painting <em><a href="https://www.moma.org/collection/works/79018">The Persistence of Memory</a></em> (now housed at the Museum of Modern Art in New York). He also used an army of ants to signify the decay of time and life’s impermanence.</p>
<h2>All is not not what it appears</h2>
<p><em>Portrait of a Carthusian</em>, the most famous portrait featuring a fly, now in the Metropolitan Museum in New York, was painted by Petrus Christus in 1446. It depicts a bearded monk. The fly perched on the ledge in front of him signifies we’re entering a zone where all is not what it appears: we might say that what seems real is only an illusion. Or, perhaps the artist has enhanced “<a href="https://www.metmuseum.org/art/collection/search/435896">the quality of the subject’s ‘real’ presence by the fly resting momentarily on the fictive frame</a>,” according to the museum. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/362730/original/file-20201009-19-1f4p0ga.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Painting of a bearded monk with a fly painted on the frame." src="https://images.theconversation.com/files/362730/original/file-20201009-19-1f4p0ga.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/362730/original/file-20201009-19-1f4p0ga.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=817&fit=crop&dpr=1 600w, https://images.theconversation.com/files/362730/original/file-20201009-19-1f4p0ga.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=817&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/362730/original/file-20201009-19-1f4p0ga.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=817&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/362730/original/file-20201009-19-1f4p0ga.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1027&fit=crop&dpr=1 754w, https://images.theconversation.com/files/362730/original/file-20201009-19-1f4p0ga.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1027&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/362730/original/file-20201009-19-1f4p0ga.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1027&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">‘Portrait of a Carthusian’ (1446), by Petrus Christus, oil on wood. Held at the Metropolitan Museum of Art, New York.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Christus_carthusian.jpg">(Wikimedia Commons)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Entomologist Ron Cherry has explored how <a href="https://doi.org/10.1093/ae/57.2.82">insects have long-standing mythological associations with death</a>. In Renaissance thought, which tended to blend medieval fabulist tales about nature with ideas about religion, flies were considered to represent <a href="https://books.google.ca/books/about/An_Illustrated_Encyclopaedia_of_Traditio.html?id=0P86CwAAQBAJ&redir_esc=y">supernatural power, mostly associated with evil and corruption, because they seemed to be spontaneously born from decaying fruit and rotting organic matter</a>. </p>
<p>In the book of Exodus in the Bible, God mustered <a href="https://sojo.net/articles/5-bible-verses-about-flies">swarms of flies</a> as <a href="https://www.biblegateway.com/passage/?search=Exodus%208&version=NIV">punishment</a>. They were harbingers of worse things, like pestilence and death. That’s a lot of deliverables for a bunch of tiny flies. </p>
<p>The point is that flies still remind us of unpleasant things, or as <a href="https://www.theatlantic.com/ideas/archive/2020/10/what-vp-debate-was-like-sound-off/616654/">commentator David Frum noted, unpleasant things in a presidency we’d rather ignore</a> — which is why, I suspect, <a href="https://www.cnn.com/2020/09/02/politics/donald-trump-coronavirus-election-2020-biden/index.html">given the administration’s record</a>, some people found it so delightful.</p><img src="https://counter.theconversation.com/content/147815/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sally Hickson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Flies have long held symbolic meaning in the history of art. In portraits made in Renaissance Europe, the presence of a fly symbolizes the transience of human life.Sally Hickson, Associate Professor, Art History, University of GuelphLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1308222020-02-02T09:54:00Z2020-02-02T09:54:00ZWe found a way to trap stable flies: their dung preferences helped us<figure><img src="https://images.theconversation.com/files/312783/original/file-20200130-41476-sr4ljj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Female stable flies make careful choices about where to lay their eggs.</span> <span class="attribution"><span class="source">Cosmin Manci/Shutterstock</span></span></figcaption></figure><p>Stable flies (<em>Stomoxys calcitrans</em>) are cold-blooded pests. They feed on the blood of their hosts, which include cattle, camels, horses, dogs and humans. During their feeding they can mechanically transmit viruses and bacteria that cause diseases like <a href="https://academic.oup.com/jme/article/48/3/656/884252">West Nile fever</a>, <a href="https://doi.org/10.2987/10-6070.1">Rift Valley fever</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC260614/">anthrax</a>.</p>
<p>They are found in <a href="https://www.cabi.org/isc/datasheet/63296">most countries</a> around the world, and are particularly common where their livestock hosts are farmed. That’s because they breed on animal dung.</p>
<p>It’s in the breeding process that something surprising emerges about these insects. Our new research shows that female stable flies carefully choose where they lay their eggs to ensure their offspring have the best start in life. It seems the phrase “mother knows best” is true even for flies.</p>
<p>I worked with my PhD student, <a href="https://www.researchgate.net/profile/Bernard_Steve_Baleba">Steve Baleba</a>, and colleagues from the International Centre of Insect Physiology and Ecology (<a href="http://www.icipe.org/">icipe</a>) in Kenya to find out which types of dung female stable flies preferred for laying their eggs. Knowing this – and the information they use to select it – meant we could explore ways to manage their populations. </p>
<p>We found that the flies favoured donkey and sheep dung, so we added the chemicals characteristic of these dung types to traps designed to catch stable flies. This led to a <a href="https://www.nature.com/articles/s41598-019-40479-9">400% increase in the number of flies trapped</a>. More importantly, the traps caught more female stable flies, large numbers of which were ready to lay eggs and contribute to the next generation. This is a valuable way to reduce fly numbers, protect animals and humans, and control the spread of dangerous diseases.</p>
<h2>Pick and choose</h2>
<p>We ran a series of experiments to identify preferred dung types for egg-laying by females and to find out why they were chosen and how flies identified the best dung to use.</p>
<p>Stable flies <a href="https://www.nature.com/articles/s41598-019-40479-9">preferred to lay their eggs on donkey and sheep dung</a> rather than the dung of buffalo, camels, elephants, giraffes or zebra – or controls of grass or moist sand. </p>
<p>And their decision had consequences. The larvae that hatched from eggs laid in donkey and sheep dung developed faster and were larger at the end of the larval stage. This meant that the adults were <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-019-3483-y">heavier and had larger wings</a> than their peers, which may improve their flight performance. </p>
<p>The improved performance of offspring developing in donkey and sheep dung was closely correlated with higher elemental nitrogen, potassium and zinc content in the dung. In contrast, camel and cow dung – which the flies did not choose – had relatively low concentrations of these elements, and had higher carbon, calcium and water content.</p>
<p>Females also preferred to lay their eggs in dung that was <a href="https://www.frontiersin.org/articles/10.3389/fevo.2020.00005/full">free of competitors and parasites</a>. If dung already contained stable fly larvae – even as few as ten – females laid fewer eggs than on dung with no larvae. Similarly, if dung was already being used by housefly (<em>Musca domestica</em>) larvae, stable flies laid fewer eggs, although this effect was only seen when at least 20 housefly larvae were present. When presented with dung containing parasitic mites (<em>Macrocheles muscaedomesticae</em>), female stable flies also avoided laying eggs. </p>
<p>All these choices benefited the flies’ offspring. They were larger, and more of them survived to reach adulthood if they developed without competition. In the absence of parasitic mites, more eggs hatched, more larvae survived to the pupal stage, and adults survived for longer.</p>
<h2>Common sense</h2>
<p>Stable flies decide where to lay their eggs using sight and smell. Vision is important for avoiding dung containing parasitic mites. We know this because the same number of egg clutches were laid on dung with and without mites when we tested egg-laying in the dark. This surprised us because at least one other fly species (<em>Drosophila hydei</em>) seems to avoid mite infection using their senses of <a href="https://www.journals.uchicago.edu/doi/abs/10.1086/691704">smell and touch</a>.</p>
<p>Either taste or smell is involved with avoiding competition because even in the dark, females laid fewer clutches on dung with competitors. To select between different dung types, female stable flies use their sense of smell. We found that two chemicals characteristic of donkey and sheep dung (β-citronellene and carvone, respectively) encouraged stable flies to lay their eggs on moist sand that had been treated with these chemicals.</p>
<p>We believe that the decision by female stable flies to lay eggs on a preferred dung type is probably hard-wired into their sensory and nervous systems. This is because we found <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/een.12748">no evidence for females learning</a> to prefer one dung type over another based on the dung they themselves developed in. That said, larvae that accidentally wander away from a preferred dung type have a short-term memory that helps them to return to it.</p>
<p>These results all show that stable flies evolved to find the best conditions for the survival of their offspring. </p>
<p>Armed with this information we were able to test traps using the chemicals β-citronellene and carvone. As I’ve said, this was hugely successful. The next step is to optimise the blend of these chemicals and commercialise it. We also want to find out which chemicals stable flies use to avoid competition. These could be developed into repellents to protect humans and livestock from stable flies and the diseases they transmit.</p><img src="https://counter.theconversation.com/content/130822/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Weldon does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Savvy female stable flies prefer to lay their eggs on donkey and sheep dung. Knowing where they choose to do this will help us manage disease.Christopher Weldon, Associate Professor in Entomology, University of PretoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1218672019-08-14T19:58:08Z2019-08-14T19:58:08ZEye-opening discovery: 54 million year old fossil flies yield new insight into the evolution of sight<figure><img src="https://images.theconversation.com/files/287977/original/file-20190814-136208-1nfclte.jpeg?ixlib=rb-1.1.0&rect=17%2C0%2C1038%2C1025&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eyes surprise: fossil eyes from a 54 million year old cranefly.</span> <span class="attribution"><span class="source">Lindgren et al./Nature</span></span></figcaption></figure><p>Fossilised flies that lived 54 million years ago have revealed a surprising twist to the tale of how insects’ eyes evolved. These craneflies, <a href="https://www.nature.com/articles/s41586-019-1473-z">unveiled in Nature today</a>, show that insect eyes trap light the same way as human eyes, using the pigment melanin – yet another example of evolution finding similar solutions to similar problems.</p>
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Read more:
<a href="https://theconversation.com/eye-to-the-past-vision-may-be-older-than-previously-thought-10411">Eye to the past: vision may be older than previously thought</a>
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<p>Evolutionary biologists have always been fascinated by eyes. Charles Darwin, anticipating the sceptics, devoted a long explanation of how random mutation followed by natural selection could readily fashion such “organs of extreme perfection”. It is not surprising that these useful adaptations have evolved repeatedly across the animal kingdom - <a href="https://theconversation.com/humans-and-squid-evolved-same-eyes-using-same-genes-26265">octopuses and squids</a>, for instance, have independently acquired eyes uncannily similar to ours.</p>
<p>Vision is so vital that most animals today have photoreceptors of some kind. Notable exceptions include creatures that live in total darkness, such as in caves or the deep ocean. </p>
<p>Yet the fossil record of eyes is very poor. The rock record generally preserves hard parts such as bones and shells. Eyes and other soft tissues, such as nerves, veins and intestines, are preserved only under exceptional circumstances. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/287975/original/file-20190814-136230-1szhgju.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/287975/original/file-20190814-136230-1szhgju.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287975/original/file-20190814-136230-1szhgju.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=307&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287975/original/file-20190814-136230-1szhgju.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=307&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287975/original/file-20190814-136230-1szhgju.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=307&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287975/original/file-20190814-136230-1szhgju.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=386&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287975/original/file-20190814-136230-1szhgju.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=386&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287975/original/file-20190814-136230-1szhgju.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=386&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">One of the fossils that yielded the surprise discovery: a 54-million-year old cranefly from Denmark.</span>
<span class="attribution"><span class="source">Lindgren et al./Nature</span></span>
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<h2>Exceptionally preserved insect fossils</h2>
<p>Because eyes are icons of evolution yet rarely fossilised, the discovery of perfectly preserved eyes from 54 million-year-old insects is noteworthy. In their <a href="https://www.nature.com/articles/s41586-019-1473-z">new study</a>, researchers led by Johan Lindgren of Lund University in Sweden collected and analysed eyes from 23 <a href="https://australianmuseum.net.au/learn/animals/insects/crane-flies/">craneflies</a> – long-legged relatives of pesky houseflies. </p>
<p>The fossils were exquisitely preserved in sediments containing high levels of fine-grained volcanic ash. They were unearthed in what is now chilly Denmark, but back then was a tropical paradise with abundant insect life.</p>
<p>The fossilised eyes were surprisingly similar to our own eyes in one important way. The back of our eyeball, called the <a href="https://en.wikipedia.org/wiki/Choroid">choroid</a>, is dark and opaque; this protects against ultraviolet radiation and also stops stray light bouncing around and interfering with vision. In human eyes, this anti-reflective layer contains high levels of the pigment melanin, the same molecule involved in skin pigmentation (hence terms such as “melanoma”). </p>
<p>Insects, too, have dark anti-reflective layers in their eyes, but this was long thought to consist entirely of a different molecule, ommochrome. Given that insect eyes arose independently from our own and have an entirely different structure, it seems reasonable that their molecular machinery would also be different.</p>
<h2>Eyes like our own?</h2>
<p>However, detailed chemical analysis of the fossil cranefly eyes revealed that they contained human-like melanin. When the researchers had another look at the eyes of living craneflies, they were surprised to confirm the presence of melanin (as well as lots of ommochrome). It took fossils to alert us that the eyes of humans and insects both use the same shielding pigments (melanin) - yet another example of <a href="https://www.sciencedirect.com/topics/immunology-and-microbiology/convergent-evolution">convergent evolution</a>.</p>
<p>Intriguingly, the outer layers of the fossilised eyes were full of calcite, the mineral that makes up most of limestone. Not only that, but crystals in the calcite were aligned to transmit light efficiently into the eye. Yet this apparent fine engineering (a mineralised outer eye layer optimised to transmit light) was almost certainly caused by the fossilisation process, as the eyes of living craneflies are not mineralised.</p>
<p>While the fossil record can reveal, it can also mislead, if not interpreted carefully. <a href="https://australianmuseum.net.au/learn/australia-over-time/fossils/what-are-trilobites/">Trilobites</a>, the hard-shelled crab-like creatures that are among the most abundant and diverse animal fossils, are frequently found with mineralised, light-transmitting outer eye layers. These have usually been assumed to faithfully reflect their life condition: predation in ancient oceans was so intense that trilobites even armoured their eyeballs. </p>
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<a href="https://images.theconversation.com/files/287964/original/file-20190814-136176-1ld3zbu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/287964/original/file-20190814-136176-1ld3zbu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287964/original/file-20190814-136176-1ld3zbu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=806&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287964/original/file-20190814-136176-1ld3zbu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=806&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287964/original/file-20190814-136176-1ld3zbu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=806&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287964/original/file-20190814-136176-1ld3zbu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1012&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287964/original/file-20190814-136176-1ld3zbu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1012&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287964/original/file-20190814-136176-1ld3zbu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1012&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The 400-million-year old trilobite <em>Hollardops mesocristata</em> is widely thought to have had mineralised eyes.</span>
<span class="attribution"><span class="source">Daderot / wikimedia commons</span></span>
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<p>Lindgren and colleagues warn against this interpretation: perhaps the trilobite’s “protective goggles” only appeared after fossilisation, just as in the craneflies. However, this interpretation will likely be debated. <a href="https://www.amnh.org/research/paleontology/collections/fossil-invertebrate-collection/trilobite-website/the-trilobite-files/trilobite-eyes">Trilobite eyes</a> seem to have been unusually rigid and resilient in real life, as they are preserved in three dimensions much more often than eyes of other animals. They also have certain optical properties that make more sense when the rigid outer layer is accepted as real.</p>
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Read more:
<a href="https://theconversation.com/the-eyes-have-it-how-vision-may-have-driven-fishes-onto-land-73060">The eyes have it: how vision may have driven fishes onto land</a>
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<p>A disagreement between a few palaeontologists might seem a bit arcane, but these debates can have real-world relevance. Most famously, the <a href="https://www.smithsonianmag.com/science-nature/when-carl-sagan-warned-world-about-nuclear-winter-180967198/">concept of nuclear winter was directly inspired by discussion of how the dinosaurs went extinct</a>, when a meteorite impact enveloped the world in a cloud of dust, deep-freezing the entire biosphere. </p>
<p>Granted, the debate over how insect and trilobite eyes functioned is unlikely to influence world peace, but it might still have useful applications. For example, the way trilobite lenses (apparently) provide constant acuity while being totally rigid has inspired bioengineers to fashion <a href="https://researchmatters.in/article/scientists-fabricate-aspheric-lenses-inspired-extinct-trilobites">high-performance optical devices</a> with uses spanning microscopy to laser physics.</p><img src="https://counter.theconversation.com/content/121867/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Lee has received relevant research funding from the Australian Research Council</span></em></p>Fossil flies from what is now Denmark reveal some striking similarities between insect eyes 54 million years ago, and our own vision today.Mike Lee, Professor in Evolutionary Biology (jointly appointed with South Australian Museum), Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1118882019-02-20T19:01:09Z2019-02-20T19:01:09ZZebra’s stripes are a no fly zone for flies<figure><img src="https://images.theconversation.com/files/259740/original/file-20190219-43264-zcnuyx.JPG?ixlib=rb-1.1.0&rect=265%2C130%2C2656%2C1864&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientific testing has zeroed in on the advantages of a zebra's striped coat.</span> <span class="attribution"><span class="source">Tim Caro</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Zebras are famous for their contrasting black and white stripes – but until very recently no one really knew why they sport their unusual striped pattern. It’s a question that’s been discussed as far back as 150 years ago by great Victorian biologists like Charles Darwin and Alfred Russel Wallace. </p>
<p>Since then many ideas have been put on the table but only in the last few years have there been serious attempts to test them. These ideas fall into four main categories: Zebras are striped to evade capture by predators, zebras are striped for social reasons, zebras are striped to keep cool, or they have stripes to avoid attack by biting flies.</p>
<p>Only the last one stands up to scrutiny. And <a href="https://doi.org/10.1371/journal.pone.0210831">our latest research</a> helps fill in more of the details on why.</p>
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<a href="https://images.theconversation.com/files/259741/original/file-20190219-43264-1g32h5i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/259741/original/file-20190219-43264-1g32h5i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/259741/original/file-20190219-43264-1g32h5i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/259741/original/file-20190219-43264-1g32h5i.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/259741/original/file-20190219-43264-1g32h5i.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/259741/original/file-20190219-43264-1g32h5i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/259741/original/file-20190219-43264-1g32h5i.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/259741/original/file-20190219-43264-1g32h5i.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Camouflage? ID? Natural air conditioning? No, no and no.</span>
<span class="attribution"><span class="source">Tim Caro</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<h2>What’s the advantage of zebra stripes?</h2>
<p>Could stripes help zebras avoid becoming a predator’s meal? There are many problems with this idea. Field experiments show that zebras stand out to the human eye when they’re among trees or in grassland even when illumination is poor – <a href="https://press.uchicago.edu/ucp/books/book/chicago/Z/bo24838630.html">they appear far from camouflaged</a>. And when fleeing from danger, zebras do not behave in ways to maximize any confusion possibly caused by striping, making hypothetical <a href="https://press.uchicago.edu/ucp/books/book/chicago/Z/bo24838630.html">ideas about dazzling predators untenable</a>.</p>
<p>Worse still for this idea, the eyesight of lions and spotted hyenas is much weaker than ours; these predators can only resolve stripes when zebras are very close up, at a distance when they can likely hear or smell the prey anyway. So stripes are <a href="https://doi.org/10.1371/journal.pone.0145679">unlikely to be of much use in anti-predator defense</a>.</p>
<p>Most damaging, <a href="https://doi.org/10.1017/S0952836905007508">zebras are a preferred prey item for lions</a> – in study after study across Africa, lions kill them more than might be expected from their numerical abundance. So stripes cannot be a very effective anti-predator defense against this important carnivore. So much for the evading-predators hypothesis.</p>
<p>What about the idea that stripes help zebras engage with members of their own species? Every zebra has a unique pattern of striping. Could it be useful in individual recognition? This possibility seems highly unlikely given that uniformly colored domestic horses can <a href="https://doi.org/10.1073/pnas.0809127105">recognize other individuals by sight and sound</a>. Striped members of the horse family <a href="https://press.uchicago.edu/ucp/books/book/chicago/Z/bo24838630.html">do not groom each other</a> – a form of social bonding – more than unstriped equid species either. And very unusual <a href="https://doi.org/10.1111/aje.12463">unstriped individual zebras are not shunned by group members</a>, and they breed successfully.</p>
<p>What about some kind of defense against the hot African sun? Given that black stripes might be expected to absorb radiation and white stripes reflect it, one idea proposed that stripes set up convection currents along the animal’s back, thereby cooling it.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/259773/original/file-20190219-43255-pia2ut.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/259773/original/file-20190219-43255-pia2ut.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/259773/original/file-20190219-43255-pia2ut.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=325&fit=crop&dpr=1 600w, https://images.theconversation.com/files/259773/original/file-20190219-43255-pia2ut.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=325&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/259773/original/file-20190219-43255-pia2ut.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=325&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/259773/original/file-20190219-43255-pia2ut.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=409&fit=crop&dpr=1 754w, https://images.theconversation.com/files/259773/original/file-20190219-43255-pia2ut.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=409&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/259773/original/file-20190219-43255-pia2ut.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=409&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Field experiments tested how various coloring patterns affected the temperature of water-filled barrels.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s41598-018-27637-1">Gábor Horváth in Scientific Reports</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Again, this seems improbable: Careful experiments in which large water barrels were draped in striped or uniform colored pelts, or were painted striped or unstriped, showed <a href="https://doi.org/10.1038/s41598-018-27637-1">no differences in internal water temperatures</a>. Moreover thermographic measurements of zebra, impala, buffalo and giraffe in the wild show that zebras <a href="https://press.uchicago.edu/ucp/books/book/chicago/Z/bo24838630.html">are no cooler</a> than these other species with whom they live.</p>
<p>The last idea for striping sounds preposterous at first blush – stripes stop biting insects from obtaining a blood meal – but it has a lot of support.</p>
<p>Early experiments in the 1980s reported that tsetse flies and horseflies <a href="https://doi.org/10.1098/rspb.2009.2202">avoid landing on striped surfaces</a> and has been <a href="https://press.uchicago.edu/ucp/books/book/chicago/Z/bo24838630.html">confirmed more recently</a> . </p>
<p>Most convincingly, however, are data from across the geographic range of the seven living species of equids. Some of these species are striped (zebras), some are not (Asiatic asses) and some are partially striped (African wild ass). Across species and their subspecies, <a href="https://doi.org/10.1038/ncomms4535">intensity of striping closely parallels biting fly annoyance</a> in Africa and Asia. That is, wild equids indigenous to areas where annoyance from horseflies is prolonged over the year are those most likely to have marked striping patterns.</p>
<p>We think that the reason equids need to be striped in Africa is that African biting flies carry diseases such as trypanosomiasis, African horse sickness and equine influenza which can be fatal to equids. And zebras are <a href="https://press.uchicago.edu/ucp/books/book/chicago/Z/bo24838630.html">particularly susceptible to probing by biting fly mouthparts</a> because of their short cropped coats. Having a fur pattern that helped evade flies and the deadly diseases they carried would be a strong advantage, meaning stripes would be passed on to future generations. </p>
<h2>Testing the idea that stripes and flies don’t mix</h2>
<p>But how do stripes actually exert their influence on biting flies? <a href="https://doi.org/10.1371/journal.pone.0210831">We set out to examine this</a> at a livery in Somerset, U.K., where horseflies collect in the summer.</p>
<p>We were lucky enough to work with Terri Hill, the livery’s owner. We could get very close to her horses and tame plains zebras, allowing us to actually watch flies landing or flying past the equids. We also videoed fly behavior around the animals, and put different colored coats on horses.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/259739/original/file-20190219-43284-pjvkgx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/259739/original/file-20190219-43284-pjvkgx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/259739/original/file-20190219-43284-pjvkgx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=216&fit=crop&dpr=1 600w, https://images.theconversation.com/files/259739/original/file-20190219-43284-pjvkgx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=216&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/259739/original/file-20190219-43284-pjvkgx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=216&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/259739/original/file-20190219-43284-pjvkgx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=271&fit=crop&dpr=1 754w, https://images.theconversation.com/files/259739/original/file-20190219-43284-pjvkgx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=271&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/259739/original/file-20190219-43284-pjvkgx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=271&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Uniformly colored horses received many more approaches and touchdowns by bothersome flies than did zebras.</span>
<span class="attribution"><span class="source">Martin How</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>It is important to remember that flies have much poorer vision than people. We found that zebras and horses received a similar number of approaches from horseflies, probably attracted by their smell – but zebras experienced far fewer landings. Around horses, flies hover, spiral and turn before touching down again and again. In contrast, around zebras flies either flew right past them or made a single quick landing and flew off again.</p>
<p>Frame by frame analyses of our videos showed that flies slowly decelerated as they approached brown or black horses before making a controlled landing. But they failed to decelerate as they approached zebras. Instead they would fly straight past or literally bump into the animal and bounce off.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/259746/original/file-20190219-43291-1u27ygw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/259746/original/file-20190219-43291-1u27ygw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/259746/original/file-20190219-43291-1u27ygw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/259746/original/file-20190219-43291-1u27ygw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/259746/original/file-20190219-43291-1u27ygw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/259746/original/file-20190219-43291-1u27ygw.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/259746/original/file-20190219-43291-1u27ygw.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/259746/original/file-20190219-43291-1u27ygw.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Striped coats on plain-colored horses reduced the number of fly incursions on covered parts of the body.</span>
<span class="attribution"><span class="source">Tim Caro</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>When we placed black coats or white coats or striped coats on the same horse so as to control for any differences in animal behavior or smell, again flies did not land on the stripes. But there was no difference in landing rates on the horse’s naked head, showing that stripes exert their effect close up but do not impede fly approaches at a distance. </p>
<p>And it showed us that striped horse coats, currently sold by two companies, really do work.</p>
<p><iframe id="BBgEP" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/BBgEP/4/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>So now that we know that stripes affect horseflies really close up, not at a distance, what is actually going on inches away from the host? One idea is that the <a href="https://doi.org/10.1016/j.zool.2013.10.004">stripes set up an optical illusion</a> that disrupts the expected pattern of movement the fly experiences as it approaches the zebra, preventing it from landing properly. Another idea is that flies don’t see the zebra as a solid entity but a series of thin black objects. Only when very close do they realize that they’re going to hit a solid body and instead veer off. We are looking into these possibilities now. </p>
<p>So our basic research on fly behavior is not only telling us why zebras are so beautifully striped, but it has real implications for the horse-wear industry, with the potential to make riding and horse maintenance less painful for horse and rider alike.</p><img src="https://counter.theconversation.com/content/111888/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>How the zebra got its stripes is not only a just-so story, but an object of scientific inquiry. New research suggests that stripes help zebras evade biting flies and the deadly diseases they carry.Tim Caro, Professor of Wildlife, Fish & Conservation Ecology, University of California, DavisMartin How, Research Fellow in Biological Sciences, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1116292019-02-17T18:57:20Z2019-02-17T18:57:20ZThe battle against bugs: it’s time to end chemical warfare<figure><img src="https://images.theconversation.com/files/259221/original/file-20190215-56220-4e8qzx.jpg?ixlib=rb-1.1.0&rect=42%2C7%2C4702%2C3144&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Does it really pay to spray?</span> <span class="attribution"><span class="source">Dmitry Syshchikov/Shutterstock</span></span></figcaption></figure><p>Insects are important wildlife often overlooked in urban habitats. What we do notice are the cockroaches, ants and mosquitoes in and around our homes. All too often we reach for the insect spray. </p>
<p>But not all insects are pests – a wide variety of them help keep our cities healthy. They pollinate plants, feed other wildlife, recycle our rubbish, and eat other insect pests. Insects are <a href="https://www.nature.com/articles/srep40970">vital to our well-being</a>. </p>
<p>Unfortunately, like many other wild animals, insects are under threat. A <a href="https://www.sciencedirect.com/science/article/abs/pii/S0006320718313636">recent study</a> warned that 40% of the world’s insect species face the prospect of extinction, amid threats such as climate change, habitat loss, and humanity’s overenthusiastic use of synthetic chemicals.</p>
<p>Australians use large amounts of pesticides to tackle creepy crawlies in their homes and gardens. But our fondness for fly spray has potentially serious <a href="https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.12211">impacts on urban ecosystems</a> and public health. </p>
<p>We need a more sustainable way to deal with urban insect pests. Our <a href="https://link.springer.com/article/10.1007/s10340-019-01087-8">recently published article in the Journal of Pest Science</a> outlines some of the ways to do it.</p>
<h2>What’s wrong with pesticides anyway?</h2>
<p>Since becoming publicly available in the 1950s, insect sprays have been a popular way to deal with cockroaches, flies, moths, and ants around the home and backyard, and are also widely used by local councils to keep pests at bay. But what may have been effective in the past won’t necessarily work in the future, or may have unintended consequences.</p>
<p>Many pests, such as <a href="https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-016-1346-3">mosquitoes</a>, are now becoming resistant to commonly used products. In parts of the world affected by diseases such as dengue, this jeopardises our ability to control outbreaks.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/chemical-or-natural-whats-the-best-way-to-repel-mozzies-36879">Chemical or natural: what's the best way to repel mozzies?</a>
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</em>
</p>
<hr>
<p>Another, perhaps wider, problem is that indiscriminate use of insecticides can kill more than just pests. Many species on which we rely for keeping our backyard gardens, bushland, wetlands and parks healthy can become collateral damage. This includes predatory species that can themselves help keep pests under control. As pest species often reproduce faster than their predators (a pattern that’s likely to be <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0059687">reinforced by climate change</a>), we can get trapped in a cycle in which pest numbers bounce back higher than ever.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/258963/original/file-20190214-1754-plnwkk.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/258963/original/file-20190214-1754-plnwkk.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/258963/original/file-20190214-1754-plnwkk.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/258963/original/file-20190214-1754-plnwkk.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/258963/original/file-20190214-1754-plnwkk.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/258963/original/file-20190214-1754-plnwkk.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/258963/original/file-20190214-1754-plnwkk.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Many wasps are predatory and specialise in eating insects that can be pests around the home.</span>
<span class="attribution"><span class="source">Manu Saunders</span></span>
</figcaption>
</figure>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/five-reasons-not-to-spray-the-bugs-in-your-garden-this-summer-85673">Five reasons not to spray the bugs in your garden this summer</a>
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</em>
</p>
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<h2>How do we do things differently?</h2>
<p>Fortunately, there are alternatives to chemical pest control that don’t harm your household or the environment. For centuries, sustainable agriculture systems have used environmentally friendly approaches, and city-dwellers can take a leaf from their books.</p>
<p><a href="https://www.epa.nsw.gov.au/your-environment/pesticides/integrated-pest-management">Integrated pest management</a> is one such sustainable approach. It focuses on prevention rather than treatment, and uses environmentally friendly options such as biological control (using predators to eat pests) to safeguard crops. Chemical insecticides are used only as a last resort.</p>
<p>There are many other farming practices that support sustainable pest control; these focus on behavioural change such as keeping areas clean, or simple physical controls such as fly mesh or netting around fruit trees. </p>
<p>Adopting these methods for urban pest control isn’t necessarily straightforward. There might be local regulations on particular pest control activities, or simply a lack of knowledge about urban pest ecology.</p>
<p>For urgent pest situations, it may be more expensive and time-consuming to set up a biological control program than to arrange the spraying of an insecticide. Insecticides take effect immediately, whereas biological control takes longer to have an effect. Prevention, the cornerstone of integrated pest management, requires careful planning before pests become a nuisance. </p>
<p>The goal of integrated pest management is <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/ps.1247">not to eliminate insect pests entirely</a>, but rather to reduce their numbers to the point at which they no longer cause a problem. By this logic, chemical insecticides should only be used if the economic damage caused by the pests outweighs the cost of the chemicals. If you hate the idea of a single cockroach living anywhere nearby, this might require you to adjust your mindset.</p>
<h2>What can I do at home?</h2>
<p>Don’t give pests opportunities. Be mindful of how we produce and dispose of waste. Flies and cockroaches thrive in our rubbish, but they can be <a href="https://www.ncbi.nlm.nih.gov/pubmed/19672400">effectively managed</a> by ensuring that food waste is stored in insect-proof containers, recycled, or properly disposed of. Don’t leave buckets of water around the backyard, as this invites mosquitoes to breed.</p>
<p>Don’t open your door to pests. Seal cracks and crevices in the outside of your house, and ensure there are screens on your doors and windows. </p>
<p>Support the animals that control insect pests – they’ll <a href="https://www.sciencedirect.com/science/article/pii/S1049964405000733">do the hard work for you</a>! In particular, don’t be so quick to kill spiders and wasps, because they prey on pests in your home and garden.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/258962/original/file-20190214-1721-1l853dx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/258962/original/file-20190214-1721-1l853dx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/258962/original/file-20190214-1721-1l853dx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/258962/original/file-20190214-1721-1l853dx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/258962/original/file-20190214-1721-1l853dx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/258962/original/file-20190214-1721-1l853dx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/258962/original/file-20190214-1721-1l853dx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Spiders like this leaf curler will happily eat a range of pests, including ants, around your home.</span>
<span class="attribution"><span class="source">jim-mclean/flickr</span></span>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-secret-agents-protecting-our-crops-and-gardens-94304">The secret agents protecting our crops and gardens</a>
</strong>
</em>
</p>
<hr>
<h2>What can we do as a community?</h2>
<p>Urban communities can learn a lot from sustainable farming. First, there needs to be better education and support provided to the public and policy makers. <a href="https://www.centralcoast.nsw.gov.au/whats-on/council/green-living-workshop-pests-predators-and-companion-planting">Workshops run by local councils</a> and information sessions with local gardening groups are a great way to start.</p>
<p>We can also work together to help debunk the popular myth that most insects are damaging or unwanted pests. Reaching for the fly spray might be easy, but remember you may end up killing friends as well as foes.</p><img src="https://counter.theconversation.com/content/111629/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lizzy Lowe is on the board of the Australian Entomological Society. She has received funding from the American Arachnological Society and the NSW Linnean society.</span></em></p><p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology and University of Sydney, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on the biology of medically important insects. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management.</span></em></p><p class="fine-print"><em><span>Tanya Latty receives funding from AgriFutures Australia and the Australian Research Council for research related to honey bee behaviour, ecology and health. She also receives funding from the Branco Weiss Foundation for a project related to collective behaviour and swarm intelligence in ants, bees and slime moulds.</span></em></p><p class="fine-print"><em><span>Manu Saunders does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>It’s easy to whip out the fly spray, but our fondness for pesticides can bring knock-on effects such as increased resistance, and harming beneficial insects in and around our homes.Lizzy Lowe, Postdoctoral researcher, Macquarie UniversityCameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyManu Saunders, Research fellow, University of New EnglandTanya Latty, Senior Lecturer, School of Life and Environmental Sciences, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/985552018-10-21T23:11:56Z2018-10-21T23:11:56ZCurious Kids: Why do flies vomit on their food?<figure><img src="https://images.theconversation.com/files/240544/original/file-20181015-109222-bb8alf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When a fly’s feeling hungry, it will land on its food and vomit out a mix of saliva and stomach acids.</span> <span class="attribution"><span class="source">Wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em><a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a> is a series for children, where we ask experts to answer questions from kids. All questions are welcome: find out how to enter at the bottom. You might also like the podcast <a href="http://www.abc.net.au/kidslisten/imagine-this/">Imagine This</a>, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.</em></p>
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<blockquote>
<p><strong>Hi. Why do flies vomit on their food? – Lili, age 10, Adelaide.</strong></p>
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<p>Fantastic question, Lili.</p>
<p>It’s about that time of year where we start firing up the barbeques. Lucky for us, we have no problem eating our delicious sausage sandwiches because we have teeth (or even knives and forks if we’re feeling fancy) to help us break the food into smaller pieces, making it easier for us to swallow. But flies don’t have any teeth and rely on other ways to digest their food - like vomiting.</p>
<p>When a fly’s feeling hungry, it will land on its food and vomit out a mix of saliva and stomach acids. These liquids have digestive proteins that help to break down the food before it even enters the fly’s mouth, turning a solid meal into a soup. Like using a straw, the fly uses its long sucking mouthpart to slurp up its liquefied meal. Their mouthparts even have sponges at the end so they fly can suck up every last drop. </p>
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<strong>
Read more:
<a href="https://theconversation.com/curious-kids-where-do-flies-sleep-92175">Curious Kids: Where do flies sleep?</a>
</strong>
</em>
</p>
<hr>
<h2>How dirty are flies?</h2>
<p>Because some species like the common bush fly and house fly are attracted to our food, they can sometimes make us sick. This is because there can be tiny disease-causing microbes that hitch a ride on fly’s feet and are left behind on our food when the fly touches it. That’s one reason why we don’t leave our food uncovered for too long. Scientists at the <a href="https://www.csiro.au/en/Research/Collections/ANIC">CSIRO’s Australian National Insect Collection</a> are using DNA to identify which microbes are transmitted by the feet and vomit of bush flies. This will be able to answer the age old question of how dirty flies really are.</p>
<h2>Garden-friendly flies</h2>
<p>Bush flies and blowflies all vomit on their food, but other flies are a little more polite at the dinner table and don’t vomit at all. Did you know there are 30,000 known species of flies in Australia? Horse flies (sometimes called march flies) and flower flies have a sweet tooth and love to drink nectar! They use their mouthparts to reach inside a flower and suck up nectar, which is full of sugar and nutrients. As they move from flower to flower drinking nectar, the fly’s hairy beard gets covered in pollen. Did you know that flies help pollinate some of Australia’s favourite native plants like the tea tree, <em>Eucalyptus</em> and <em>Grevillea</em>? Some flies, like black and gold horse fly (<em>Osca lata</em>), drink so much nectar that their abdomens taste like honey!</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6McjzfgFB74?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Some horse flies drink so much nectar that they taste like honey.</span></figcaption>
</figure>
<p>Many flies are collected with pollen still attached to them and CSIRO Scientists are mapping the DNA from the pollen stuck to the insect’s body to identify which species of plants they pollinate.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"931362015032909826"}"></div></p>
<h2>Hard working flies</h2>
<p>Flies have many important jobs in nature that we take for granted. The larvae of flies, affectionately called maggots, love to recycle nutrients by eating dead plants and animals, and converting them into nutrients that can be used by other plants and fungi. Without flies we would be waist-deep in waste! Mosquito larvae are an important diet for fish, frogs and birds. If we wished away mosquitoes, many of these larger animals would go hungry because they won’t be able to eat their favourite wriggling food.</p>
<p>So as you enjoy your sausage sanga this summer, appreciate how we digest food and spare a thought (and serviette) for the poor, toothless fly.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-what-are-spider-webs-made-from-and-how-strong-are-they-91824">Curious Kids: What are spider webs made from and how strong are they?</a>
</strong>
</em>
</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:</em></p>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165749/original/image-20170419-32713-1kyojyz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><em>Please tell us your name, age and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/98555/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Yeates receives funding from CSIRO, the Australian Biological Resources Study, the US National Science Foundation, and holds the Schlinger endowed research position at the Australian National Insect Collection.
</span></em></p><p class="fine-print"><em><span>Dr Bryan Lessard receives funding from the CSIRO and Australian Biological Resources Study.</span></em></p>Bush flies and blowflies all vomit on their food, but other flies are a little more polite at the dinner table and don’t vomit at all.David Yeates, Director of the Australian National Insect Collection, CSIROBryan Lessard, Postdoctoral Research Fellow, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/985862018-06-20T10:16:21Z2018-06-20T10:16:21ZIn praise of the midges pestering footballers in the World Cup<p>England’s opening match in World Cup 2018 was a dramatic clash between Gareth Southgate’s Young Lions and <a href="https://www.bbc.co.uk/sport/football/44519710">several million gnats</a>, not to mention Tunisia’s wrestling footballers. England pulled a win out of the bag <a href="https://www.bbc.co.uk/sport/football/44533213">at the last minute</a> – but only after a gruelling fight with some determined insects. Those plucky gnats also had to fight off the insecticide treatments of nearby swamps and insect repellent sprays deployed by the team and the media. </p>
<p>I suppose this could open up new possibilities for product endorsement – in addition to the usual shampoo and shaving adverts – if you need to <a href="https://www.youtube.com/watch?v=GmLNoHMnvEA">shave your chest</a> and remove any unsightly insect life that might have got stuck to you during a game.</p>
<p>But, despite the bad press, these swarms of midges are a very heartening sight. The last year has seen a series of reports spotlighting the grim decline of insect abundance in Europe (notably <a href="https://www.researchgate.net/profile/Theo_Zeegers/publication/325206013_Analysis_of_insect_monitoring_data_from_De_Kaaistoep_and_Drenthe/links/5afdcf30aca272b5d80f3ae0/Analysis-of-insect-monitoring-data-from-De-Kaaistoep-and-Drenthe.pdf">long-term data from Germany</a>) which has provoked headlines of ecological Armageddon and a fond nostalgia for the days of <a href="https://theconversation.com/the-moth-snowstorm-an-environmental-call-to-arms-as-powerful-as-silent-spring-67576">bug-filled countryside jaunts</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1008714393868218368"}"></div></p>
<p>The trouble is that while bees and butterflies readily gain our sympathy, other vital groups that do much of the pollinating and other crucial work that helps keep the planet turning have a dodgier reputation. Of all the bugs, it is flies that may be the hardest to like. The ones that generally attract our attention sit around on poo, vomit on our food or bite us for blood. </p>
<p>Flies can take little solace from their place in high culture. Shakespeare points out their appetite for public casual sex (King Lear, Act 4), while the Old Testament threatens plagues on multiple occasion in Exodus, or the Book of Isiah where they are summoned from the furthest rivers (which at least shows an appreciation of the powers of gnat dispersal).</p>
<p>But we dismiss flying “pests” at our peril – and the Volgograd pitch invaders may be a particularly important group for our welfare – if we can work out what they are.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1008877657159884802"}"></div></p>
<p>The precise identification of the pesky Volgograd Diptera (fly) is uncertain: are they mosquitoes, midges or gnats? The general abundance and behaviour suggests midges – but midges come in many forms. In much of the northern temperate world the biting midges of the family Ceratopogondiae are notorious. The UK version – the Highland Midge – is credited with <a href="https://must-see-scotland.com/midges-in-scotland/">scaring away tourists</a> from Scotland. They are tiny but determined females in search of a blood meal. They get in ears, eyes and noses and make them a tickling mess. </p>
<p>However the Volgograd midges seem bigger, almost beautiful as they sparkled in the setting sun, much more like Chironomidae – so called non-biting midges. Lacking the bloodthirsty reputation of their biting cousins, it is easy to take the Chironomidae for granted – but they deserve our thanks. </p>
<h2>Fighting pollution</h2>
<p>In countries with sewage treatment works it is Chironomidae larvae that do much of the sewage processing, preventing the gross pollution of waterways. Sewage treatment commonly involves filtering out the larger debris we flush away, then dribbling the resulting liquid slowly through large gravel beds. In these gravel beds, billions of midge larvae feast on the organic soup, turning much of our waste in midge biomass. This is why sewage plants are often prized by bird watchers as the sheer quantity of flies that eventually emerge make a great food source, attracting all sorts of avian visitors.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=567&fit=crop&dpr=1 754w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=567&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/224001/original/file-20180620-137711-m0vthb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=567&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A non-biting Chironomidae on a pine needle.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/nonbiting-midget-chironomidae-on-pine-needle-285316016?src=nrw4rY3MY0hwClZjodK-_g-1-20">Shutterstock/HenrikLarsson</a></span>
</figcaption>
</figure>
<p>The midge’s larvae are tough. Some species hang on in severely degraded rivers, familiar as “blood worms” – vivid red because of haemoglobin in their bodies to glean the limited oxygen from the mud. Each midge may be tiny but hatching numbers are colossal. East African rift valley lakes may seem to smoke <a href="https://www.bbc.co.uk/programmes/p0065wmb">as rising clouds of Chironomidae</a> emerge. </p>
<p>The massive swarms can be harvested, squished into midge-balls and eaten by lakeside villagers. Midge swarms seem to show <a href="http://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1003697">remarkable collective manoeuvres</a>, individual midges adjusting velocity and direction response to their immediate neighbours, detecting shifts up to at least a centimetre away (although studies do not account for the impact of footballers waving their hands about).</p>
<p>Evening is prime time for swarms as males dance in the hope of attracting a mate, so the Volgograd kick-off was perfectly timed to attract midge trouble as millions of males, newly emerged and looking their best, hit the town. Let’s not be too down on midges. The 2-1 scoreline will encourage England fans. For those who appreciate flies, the dancing swarms will also gladden the heart.</p>
<hr>
<p><em>More evidence-based articles about football and the <a href="https://theconversation.com/uk/topics/world-cup-2018-11490?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=WorldCup2018">World Cup</a>:</em></p>
<ul>
<li><p><em><a href="https://theconversation.com/how-to-keep-footballers-fit-and-fuelled-for-a-world-cup-97803?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=WorldCup2018">How to keep footballers fit and fuelled for a World Cup</a></em></p></li>
<li><p><em><a href="https://theconversation.com/world-cup-all-the-ways-footballers-and-fans-can-be-hacked-97572?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=WorldCup2018">World Cup: All the ways footballers and fans can be hacked</a></em></p></li>
<li><p><em><a href="https://theconversation.com/world-cup-var-technology-is-transforming-the-beautiful-game-97907?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=WorldCup2018">World Cup VAR: technology is transforming the beautiful game</a></em></p></li>
</ul><img src="https://counter.theconversation.com/content/98586/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Jeffries does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Footballers came under attack from a swarm of flies on the Volgograd pitch. But there’s more to midges and gnats than meets the eye.Mike Jeffries, Associate Professor, Ecology, Northumbria University, NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/921752018-03-05T19:21:49Z2018-03-05T19:21:49ZCurious Kids: Where do flies sleep?<figure><img src="https://images.theconversation.com/files/207615/original/file-20180223-152372-1s0swrr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Flies will often sleep on the underside of leaves, to escape from heat and predators.</span> <span class="attribution"><span class="source">Mai Lam/The Conversation NY-BD-CC</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>This is an article from <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!</em> </p>
<hr>
<blockquote>
<p><strong>Where do flies sleep? You never see them still like they could be asleep. - Ruby, age 8, Giralang, ACT.</strong></p>
</blockquote>
<hr>
<p>Great question, Ruby!</p>
<p>Flies are just like us – they spend the entire day buzzing around with their friends and get pretty tired at bedtime. Before sunset, a sleepy fly will try and find a safe place to rest. Some favourite places are on the undersides of leaves, twigs, and branches, or even in tall grass or under rocks. They need a comfortable place to sleep that will shelter them from the cold, rain and wind.</p>
<p>Flies need good grip because they often sleep upside down. If they sleep on the ground, they could get eaten by a hungry bird, marsupial, or frog. </p>
<p>Like us, flies will often nap in the shade of a tree to escape the afternoon heat. If they stayed out in the sun too long, they’d get very thirsty, overheat and would, well, drop like flies.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-do-sharks-sneeze-77399">Curious Kids: Do sharks sneeze?</a>
</strong>
</em>
</p>
<hr>
<p>Of course there are also party animals, like mosquitoes, that stay up all night looking for the perfect dinner. Mosquitoes are a type of fly, and have adapted their super-sensitive eyes and antennae to see in the dark. Unfortunately for us, this means that they can use their night vision to easily find and bite us. Did you know that it’s only female mosquitoes that bite us? They need the protein in our blood to ripen their eggs. All the males are peaceful vegetarians that prefer a sugary drink like flower nectar.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/207753/original/file-20180225-108139-igka89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/207753/original/file-20180225-108139-igka89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/207753/original/file-20180225-108139-igka89.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/207753/original/file-20180225-108139-igka89.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/207753/original/file-20180225-108139-igka89.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/207753/original/file-20180225-108139-igka89.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/207753/original/file-20180225-108139-igka89.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some of Australia’s beautiful flies held at CSIRO’s Australian National Insect Collection in Canberra.</span>
<span class="attribution"><span class="source">CSIRO/Bryan Lessard</span></span>
</figcaption>
</figure>
<h2>Flies need beauty sleep too</h2>
<p>We have fine-tuned body clocks, or circadian rhythms, that help us fall asleep and wake up at about the same time each day. When the sun sets, your eye makes two sleepy proteins called <em>tim</em> and <em>per</em>. These tell your brain to go to sleep. When the sun comes up, sunlight enters your eye and breaks these proteins, letting you wake up and start your day. </p>
<p>Flies and other daytime animals also have these sleepy proteins in their eyes. For nocturnal animals, like most mosquitoes, the cycle is reversed.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-do-animals-sleep-like-people-do-snails-sleep-in-their-shells-90941">Curious Kids: Do animals sleep like people? Do snails sleep in their shells?</a>
</strong>
</em>
</p>
<hr>
<p>Have you ever wondered why adults say you shouldn’t stare at your screen at night? This is because the blue light from a phone, tablet or computer screen can stop these sleepy proteins from telling your brain to get tired. This also happens to flies when they are trapped in our kitchen and kept awake by the fluorescent light.</p>
<h2>Fun fly facts</h2>
<p>You’ve probably noticed a lot more flies buzzing around in summer than winter. This is because flies and other insects are cold-blooded, meaning they can’t keep warm themselves and their body temperature is affected by the outside temperature. </p>
<p>In the summer when it’s hot, flies are super active and buzz around all day. In winter, adult flies are too cold to move and die off. At the same time, the larvae stay in the cocoon, or pupal phase, waiting to turn into adults when spring starts. When the season changes, the flowers begin to bloom and the newly hatched adult flies have nectar to drink. While they drink, they also get covered in pollen and help pollinate the plant. </p>
<p>Did you know that without flies, there would be no chocolate? This is because the only known pollinator of the cocoa plant that gives us chocolate is a tiny fly, about the size of a pin head.</p>
<p>So the next time you’re in the garden on a hot day, check the undersides of leaves and try to spot a sleepy fly!</p>
<hr>
<p><em>Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:</em></p>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168011/original/file-20170505-21620-huq4lj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><em>Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.</em></p><img src="https://counter.theconversation.com/content/92175/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Bryan Lessard receives funding from the Australian Biological Resources Study.</span></em></p>Flies need good grip because they often sleep upside down.Bryan Lessard, Postdoctoral Research Fellow, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/897552018-02-06T19:15:47Z2018-02-06T19:15:47ZThis is why you won’t be able to swat that fly<figure><img src="https://images.theconversation.com/files/202499/original/file-20180118-158528-1c066zd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fly's eye view of a rapidly approaching swatter.</span> <span class="attribution"><span class="source">Cameron Webb (NSW Health Pathology)</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Summer in Australia is defined by sport, but the most-played sport isn’t cricket or tennis – it’s fly swatting. Have you ever tried to swat a fly? You can swipe, slap, slash or swoosh your hands at these sometimes-annoying backyard pests and almost always miss.</p>
<p>Fly swatting is as challenging a sport you’ll face this summer, but why is it so hard to squish these little beasts?</p>
<hr>
<p><em><strong>Read more: <a href="https://theconversation.com/buzz-buzz-slap-why-flies-can-be-so-annoying-52296">Buzz, buzz, slap! Why flies can be so annoying</a></strong></em></p>
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<h2>An annoyance or health risk?</h2>
<p>There are <a href="https://australianmuseum.net.au/flies-and-mosquitoes-order-diptera">thousands of species of fly in Australia</a>. The vast majority pose little pest or public health threat to people. </p>
<p>Flies actually play an <a href="http://www.news.com.au/technology/science/animals/for-the-love-of-flies-dr-bryan-lessards-passion-for-bugs-could-prove-very-useful/news-story/c6ebbf7275022377f09103c91d10b24c">important role in our local environment</a> as food for predators like frogs and birds, nutrient recyclers in native forests or gardens, and <a href="https://theconversation.com/from-warm-to-swarm-why-insect-activity-increases-in-summer-69637">biological control agents</a> for other insect pests.</p>
<p>Some of the peskiest flies are some of the most effective <a href="https://blog.csiro.au/pollinators-in-kosciuszko-national-park/">pollinators</a>. Blowflies can carry <a href="http://www.abc.net.au/news/rural/2015-06-12/new-study-shows-flies-not-bees-are-mango-farmers-best-friend/6540674">double the amount of pollen of a honeybee</a> and could become the new golden child of Australian agriculture. For these reasons we shouldn’t reach <a href="https://theconversation.com/five-reasons-not-to-spray-the-bugs-in-your-garden-this-summer-85673">straight for the insect sprays</a> to kill them off.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/202765/original/file-20180122-110100-1h0pwbc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/202765/original/file-20180122-110100-1h0pwbc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/202765/original/file-20180122-110100-1h0pwbc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/202765/original/file-20180122-110100-1h0pwbc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/202765/original/file-20180122-110100-1h0pwbc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/202765/original/file-20180122-110100-1h0pwbc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/202765/original/file-20180122-110100-1h0pwbc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/202765/original/file-20180122-110100-1h0pwbc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Flies have up to 6,000 mini lenses in each eye.</span>
<span class="attribution"><span class="source">from www.shutterstock.com</span></span>
</figcaption>
</figure>
<p>Maggots could also be beneficial for human health through the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2771513/">treatment of infected wounds</a> where traditional therapies fail. They could perhaps even be a <a href="https://theconversation.com/food-for-thought-feeding-our-growing-population-with-flies-64374">future food source</a>!</p>
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<p><em><strong>Read more - <a href="https://theconversation.com/food-for-thought-feeding-our-growing-population-with-flies-64374">Food for thought: feeding our growing population with flies</a></strong></em></p>
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<p>Unfortunately, some flies are also a problem. The bloodsucking flies (such as biting midges, black flies, and horse flies) can be a serious nuisance to holiday-goers and livestock. Mosquitoes, which are actually a kind of fly, can transmit disease-causing pathogens such as <a href="https://theconversation.com/people-stay-vigilant-to-the-threat-of-malaria-even-when-infections-fall-87530">malaria</a>, <a href="https://theconversation.com/explainer-what-is-dengue-fever-8571">dengue</a> and <a href="http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1005070">Ross River virus</a>.</p>
<p>But it’s the humble housefly that’s probably one of the most-maligned pests around the home. They don’t bite but can be a persistent annoyance. Unlike the bloodsucking insects that transmit pathogens as they inject infected saliva as they bite, houseflies have been implicated in spreading hitchhiking pathogens from our garbage <a href="https://theconversation.com/should-i-throw-away-food-once-a-fly-has-landed-on-it-50895">to our food preparation areas</a> on their bodies.</p>
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<p><em><strong>Read more: <a href="https://theconversation.com/should-i-throw-away-food-once-a-fly-has-landed-on-it-50895">Should I throw away food once a fly has landed on it?</a></strong></em></p>
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<h2>Slow motion vision thwarts swatters</h2>
<p>Ever tried to swat a particularly evasive fly? It often seems they’re blessed with some kind of superpower given the ease at which they sidestep our slapping efforts.</p>
<p>The secret to this impressive evasiveness isn’t some kind of mind-reading trick of the fly. It’s their superior vision. <a href="https://link.springer.com/article/10.1007%2Fs00436-008-0939-y">Flies have up to 6,000 ommatidia</a>, or mini lenses, in each eye and can see us approach in “slow motion”. They may not have the highest resolution vision, but they’ve got some of the “fastest” vision on earth – giving them the time to quickly react and escape.</p>
<p>To the naked eye, as we prepare to swat, the fly may not seem to do anything particularly special. But scientists have <a href="http://www.sciencedirect.com/science/article/pii/S0960982208010488">employed super slow-motion video cameras</a> to track the split-second movement of flies.</p>
<p>When a fly spots a predator, or person waving their arms about, it freezes, repositions itself, and commences a choreographed dance, perfectly co-ordinating its legs and wings to lift and buzz off in the opposite direction to the incoming threat.</p>
<p>Flies can do this so quickly that our eyes can’t even follow their pre-flight manoeuvring or predict the path of their elegant escape. A split-second to us could be lifesaving for a fly. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/202909/original/file-20180122-182965-1gvhv5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/202909/original/file-20180122-182965-1gvhv5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/202909/original/file-20180122-182965-1gvhv5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/202909/original/file-20180122-182965-1gvhv5e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/202909/original/file-20180122-182965-1gvhv5e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/202909/original/file-20180122-182965-1gvhv5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/202909/original/file-20180122-182965-1gvhv5e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/202909/original/file-20180122-182965-1gvhv5e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A fly about to take off.</span>
<span class="attribution"><span class="source">Mt Anne Scaptia jacksonii</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>A few options for fewer flies</h2>
<p>If flies are a persistent problem in and around your home there are a few options for relief. Screening windows and doors will assist in keeping them outside. Reducing opportunities for them to breed is important too, so keep the backyard clean and tidy. Locate composting areas as far away from your house as possible. Reduce the amount of waste (both garbage and pet droppings) around the backyard and keep garbage bins covered. </p>
<p><a href="http://www.abc.net.au/news/2017-07-09/flesh-eating-fascination-tasmanian-native-carnivorous-plants/8677232">Native carnivorous plants</a> like sundews, bladderworts and pitcher plants could also be a trendy addition to your garden to help keep the unwanted fly population down. </p>
<p>A range of insecticides are available but remember they’ll be <a href="https://theconversation.com/neonicotinoids-linked-to-wild-bee-and-butterfly-declines-in-europe-and-us-63999">harmful to other insects too</a>. As with many other urban insect pests, including <a href="https://theconversation.com/everything-you-never-wanted-to-know-about-bed-bugs-and-more-89049">bed bugs</a> and <a href="https://theconversation.com/heres-how-you-beat-indestructible-head-lice-63594">head lice</a>, <a href="http://www.mdpi.com/2075-4450/7/1/2/htm">resistance to commonly used insects sprays</a> has been recorded in houseflies – so where you can avoid using these products, the better. </p>
<p>You could try a technology more than 100 years old: <a href="http://www.nytimes.com/2012/05/27/magazine/who-made-that-fly-swatter.html">the fly swat</a>. But, in reality, you may as well give up now. Flies have spent millions of years perfecting the sweet escape and too easily avoid our sluggish attempts at swatting.</p><img src="https://counter.theconversation.com/content/89755/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Webb and the Department of Medical Entomology, NSW Health Pathology, have been engaged by a wide range of insect repellent and insecticide manufacturers to provide testing of products and provide expert advice on mosquito biology. Cameron has also received funding from local, state and federal agencies to undertake research into mosquito-borne disease surveillance and management.</span></em></p><p class="fine-print"><em><span>Bryan Lessard receives funding from The Australian Biological Resources Study.</span></em></p>Why are flies so easily able to evade our attempts to swat them?Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyBryan Lessard, Postdoctoral Research Fellow, CSIROLicensed as Creative Commons – attribution, no derivatives.