tag:theconversation.com,2011:/africa/topics/hidden-housemates-24843/articlesHidden housemates – The Conversation2022-01-16T18:57:22Ztag:theconversation.com,2011:article/1744012022-01-16T18:57:22Z2022-01-16T18:57:22ZThe Singapore-inspired idea for using super for housing that could cut costs 50%<figure><img src="https://images.theconversation.com/files/440818/original/file-20220114-19-glxhyy.png?ixlib=rb-1.1.0&rect=221%2C395%2C2928%2C1652&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>During the past four decades in which home ownership among Australians aged 25-34 has sunk from around <a href="https://www.aihw.gov.au/reports/australias-welfare/home-ownership-and-housing-tenure">60% to 45%</a>, home ownership among the same age group in Singapore has climbed from around <a href="https://tablebuilder.singstat.gov.sg/table/TS/M810401">60% to 88%</a>.</p>
<p>There’s a good chance that’s because Singapore is doing something right.</p>
<p>What Singapore has that Australia does not is a public housing developer, the <a href="https://www.hdb.gov.sg/cs/infoweb/homepage">Housing Development Board</a>, which puts new dwellings on public and reclaimed land, provides mortgages, and allows buyers to use their compulsory retirement savings (what Australians call superannuation) for both a deposit and repayments.</p>
<p>There’s more to it than that. It limits eligibility by income and age, requires owners to hang on to the property for five years, and limits their resale to only other eligible buyers.</p>
<p>Eight in ten of all the dwellings in Singapore today were built over the past half century by the Housing Development Board.</p>
<p>In a new paper released this month I suggest an Australian version called <a href="https://osf.io/nxq2u/">HouseMate</a>, that could halve the cost of buying a home.</p>
<h2>Introducing HouseMate</h2>
<ul>
<li><p>Housemate would build on underutilised crown, council, and federal land, land acquired by compulsory acquisition, or land purchased at market prices, and by tenders from private developers</p></li>
<li><p>HouseMate would sell the dwellings at a discounted price (A$300,000 on average) to Australian citizens aged over 24 and in a de facto or married relationship and to single citizens aged over 28 and over, where no household member owns property</p></li>
<li><p>HouseMate would offer loans underwritten by the federal government for up to 95% of the purchase price, charged at one percentage point above the cash rate, which at the moment would be 1.1%</p></li>
<li><p>HouseMate buyers would be permitted to use their superannuation savings and contributions for both the deposit and ongoing repayments</p></li>
<li><p>HouseMate buyers would be required to occupy the home, with limits on leasing and resale for seven years. They will own the home freehold, paying council rates, insurances, and having responsibility for maintenance and body corporate representation</p></li>
<li><p>HouseMate owners could sell after seven years. But if they sell to the private market instead of another eligible HouseMate buyer, that would trigger a waiting period of seven years before the seller became eligible for another HouseMate home, and a fee of 15% of the sale price</p></li>
</ul>
<h2>Homes for half price</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/440816/original/file-20220114-25-qr9hwk.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/440816/original/file-20220114-25-qr9hwk.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/440816/original/file-20220114-25-qr9hwk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=966&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440816/original/file-20220114-25-qr9hwk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=966&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440816/original/file-20220114-25-qr9hwk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=966&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440816/original/file-20220114-25-qr9hwk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1214&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440816/original/file-20220114-25-qr9hwk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1214&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440816/original/file-20220114-25-qr9hwk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1214&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://gameofmates.files.wordpress.com/2022/01/housemate_jan2022_vpublish.pdf">HouseMate, a proposed national institution to build new homes and sell them cheap to any citizen who does not own a home</a></span>
</figcaption>
</figure>
<p>My calculations suggest building these homes on land that would cost little (perhaps A$50,000 averaged across all types) would by itself cut the price 20-35%.</p>
<p>The lower interest rate, and the use of superannuation savings for both the deposit and repayments would cut the “after super” cost saved by as much again, cutting the “after super” cost savings 50-70%.</p>
<p>The use of superannuation savings where available makes sense. Home ownership does more for security in retirement than does super.</p>
<p>Because the use of super would be quarantined to new HouseMate homes, it would be unlikely to push up the price of existing homes.</p>
<p>No other housing policy change would do anything like as much to make homeownership cheaper, or to free up income for families at the times they need it most. </p>
<p>The changes to tax arrangements often talked about, including changes to capital gains tax and negative gearing, might on my estimate at most cut prices by as much as 10% - enough to reverse only <a href="https://www.corelogic.com.au/news/housing-values-end-year-221-higher-pace-gains-continuing-soften-multi-speed-conditions-emerge">six months</a> of the past year’s price growth.</p>
<h2>There would be critics</h2>
<p>Because HouseMate would divert first home buyers away from private
markets, private sellers would find reasons to argue it would be bad for the people it helps and somehow financially reckless or unsustainable. Banks would argue the same thing.</p>
<p>But because the non-land cost of HouseMate dwellings would be mostly covered by the purchase price (and 15% of private resale prices) and the other costs would mostly be covered by the interest margin, the budget cost would be low - on my estimate peaking at A$1.7 billion after seven years and shrinking to $640 million after 20 years.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-century-of-public-housing-lessons-from-singapore-where-housing-is-a-social-not-financial-asset-121141">A century of public housing: lessons from Singapore, where housing is a social, not financial, asset</a>
</strong>
</em>
</p>
<hr>
<p>The $1 billion or so per year would provide 30,000 affordable houses per year. Compared to the A$100 billion spent on the COVID JobKeeper scheme, that cost is a rounding error. Australia spends $125 billion per year on healthcare.</p>
<p>Each year about <a href="https://www.fresheconomicthinking.com/2016/06/the-great-australian-town-planning-give.html">$11 billion</a> is given to private landowners through
rezoning decisions. Taxing those value gains could fund HouseMate ten times over.</p>
<h2>We have got the land</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/440817/original/file-20220114-27-1sf1klu.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/440817/original/file-20220114-27-1sf1klu.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/440817/original/file-20220114-27-1sf1klu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=970&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440817/original/file-20220114-27-1sf1klu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=970&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440817/original/file-20220114-27-1sf1klu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=970&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440817/original/file-20220114-27-1sf1klu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1219&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440817/original/file-20220114-27-1sf1klu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1219&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440817/original/file-20220114-27-1sf1klu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1219&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 Australian Capital Territory has developed land for decades.</span>
<span class="attribution"><span class="source">Google Maps</span></span>
</figcaption>
</figure>
<p>The New South Wales Land and Housing Corporation has four times the net assets of Singapore’s Housing Development Board at <a href="https://www.hdb.gov.sg/-/media/doc/CCG/HDB-Financial-Statements-for-the-year-ended-31st-March-2021.pdf">$54 billion</a>. Queensland’s Housing and Public Works has <a href="https://www.hpw.qld.gov.au/__data/assets/pdf_file/0013/6160/15financialstatements.pdf">$10 billion</a> in land assets. Victoria’s Department of Families, Fairness and
Housing has <a href="https://www.dffh.vic.gov.au/sites/default/files/documents/202110/DFFH%20annual%20report%202020-21.pdf">$17 billion</a>.</p>
<p>We could start by upgrading and selling existing public housing to its tenants under HouseMate rules.</p>
<p>The Australian Capital Territory has operated this way for decades, developing low or zero cost rural land for housing and selling the homes at cost, although in recent decades it has acted more like a private developer, maximising revenue at the expense of putting people into homes.</p>
<h2>To start with, there would be bottlenecks</h2>
<p>HouseMate would be overwhelmed at first. I have suggested lotteries to allocate homes until the system ramps up. </p>
<p>Just as Medicare didn’t displace but operated alongside the private health system, HouseMate would operate parallel to the private market, adding to overall supply rather than increasing demand in the private market.</p>
<p>I’ll finish with a story. I met a Singaporean resident recently who moved to Australia to study social work. She said they don’t really have homeless people in Singapore because the Housing Development Board provided an option for almost everyone.</p>
<p>To find homeless people required moving to Australia. I think we ought to try it. What’s the worst that could happen?</p><img src="https://counter.theconversation.com/content/174401/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cameron Murray is currently a member of the Drew Pavlou Democratic Alliance.</span></em></p>HouseMate would sell homes for little more than the cost of construction, allowing the use of super for the deposit and mortgage payments.Cameron Murray, Research Fellow - Henry Halloran Trust, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/602332016-06-02T01:29:43Z2016-06-02T01:29:43ZHidden housemates: springtails are everywhere, even in your home<figure><img src="https://images.theconversation.com/files/124698/original/image-20160601-3253-1rpjgm2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Springtails come in variety of shapes and sizes. </span> <span class="attribution"><span class="source">Springtail image from www.shutterstock.com</span></span></figcaption></figure><p>You’ve probably never heard of them, let alone seen them, but it’s likely you have some in your home. <a href="http://www.environment.gov.au/biodiversity/abrs/online-resources/fauna/afd/taxa/COLLEMBOLA">Springtails</a> are only 1-2 mm long but are ubiquitous, found in every habitat except the oceans. </p>
<p>Springtails are closely related to insects – they have six legs and a head, thorax and abdomen – but are not insects because they lack wings and have soft bodies and hidden mouthparts. Springtails are known scientifically as <a href="http://www.collembola.org/">Collembola</a>.</p>
<p>Collembola are unique in carrying a jumping organ beneath the abdomen, held in place with hooks. When released, the jumping organ springs free, hitting the ground and forcing the animal to leap into the air, hence their common name.</p>
<p>In the wild, springtails can be found in leaf litter, soil, under bark, in sand, under stones, in tree canopies and even in caves and ant and termite nests. In termite nests they may control fungal growth. Most importantly, springtails have been shown to be <a href="http://www.publish.csiro.au/?paper=EA05264">useful bioindicators of environmental change</a>.</p>
<p>Some male springtails perform a complex mating dance to attract the female. Other species are carried by insects for dispersal or feeding purposes. </p>
<figure>
<iframe src="https://player.vimeo.com/video/19518709" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">A springtail mating dance as shown in David Attenborough’s Life in the Undergrowth.</span></figcaption>
</figure>
<p><a href="http://www.chaosofdelight.org/collembola/#collembola10">In Australia</a>, there are several thousand species, most found only in this country. In any garden compost heap there will be millions of individuals belonging to about ten species. Native springtails may be brightly coloured and patterned; white, if living in soil; or black if living in exposed habitats such as mountain tops, beaches or coral reefs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/124695/original/image-20160601-1425-njtuxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/124695/original/image-20160601-1425-njtuxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124695/original/image-20160601-1425-njtuxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=348&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124695/original/image-20160601-1425-njtuxr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=348&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124695/original/image-20160601-1425-njtuxr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=348&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124695/original/image-20160601-1425-njtuxr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=437&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124695/original/image-20160601-1425-njtuxr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=437&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124695/original/image-20160601-1425-njtuxr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=437&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Native springtails can be brightly coloured - this is Acanthanura from Tasmania.</span>
<span class="attribution"><span class="source">Copyright Andy Murray</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/124696/original/image-20160601-1923-14ia8zp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/124696/original/image-20160601-1923-14ia8zp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124696/original/image-20160601-1923-14ia8zp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=352&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124696/original/image-20160601-1923-14ia8zp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=352&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124696/original/image-20160601-1923-14ia8zp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=352&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124696/original/image-20160601-1923-14ia8zp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=442&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124696/original/image-20160601-1923-14ia8zp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=442&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124696/original/image-20160601-1923-14ia8zp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=442&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Another Tasmanian springtail, <em>Temeritus</em>.</span>
<span class="attribution"><span class="source">Copyright Andy Murray</span></span>
</figcaption>
</figure>
<h2>Springtails in the home</h2>
<p>Three species are commonly found inside buildings, all with an elongated bodies and belonging to the family Entomobryidae. These are introduced species, which were probably brought to Australia in soil and animal fodder before quarantine controls were put in place. </p>
<p>If you put sticky or water traps in a garage or shed, for instance, after only a day or two springtails should appear floating on the water or trapped in the glue. You might have to use a magnifying glass to see them. </p>
<p>Cellars invariably harbour several species. One unusual example was in a doctor’s surgery, where every morning springtails were found floating in the then-cooled water of the steriliser, having emerged overnight from their hiding place and fallen in.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/124700/original/image-20160601-1923-jwk2vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/124700/original/image-20160601-1923-jwk2vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124700/original/image-20160601-1923-jwk2vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124700/original/image-20160601-1923-jwk2vp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124700/original/image-20160601-1923-jwk2vp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124700/original/image-20160601-1923-jwk2vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124700/original/image-20160601-1923-jwk2vp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124700/original/image-20160601-1923-jwk2vp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This Entomobrya springtail is from the family often found in homes.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/andybadger/11563605843/in/photolist-iBQv9x-bALjjb-6hneVQ-dk21eL-cB7ZrW-cHgHzh-efgFmJ-cZBAXW-izFgcK-e265Q4-dPjvDa-63wx3f-5LiDUW-fnsCAb-61jxNm-cYtudJ-6gYhwc-dmADp8-5Tqvqs-6hneUb-bye76f-62LXWj-64apqL-9MLejR-61jxQu-iCJCff-5wtBmh-61jxU1-63jhto-5CPT3D-5uDabM-66fXwM-bDD9ft-4afLet-5UMybi-5XRUuT-5WkvUW-61fkQr-5ssoZt-4bEcRL-bmKzLg-5XRUsv-63wwWm-61jxLQ-5TLpeW-5BnyGT-cGDkiN-5N1nuj-5XRUqn-61jy1Y">Andy Murray/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Springtails are dispersed involuntarily in several ways. They can be transported in air currents and in flowing water in drains, as well as being carried in timber, packing materials and footwear, by domestic animals and on fresh vegetables and house plants. Species on vegetables could only become established in pot plant soil.</p>
<p>Household springtails feed on fungi and other microorganisms, which can be present in clean, relatively dry habitats such as within walls and under floors. </p>
<p>One species of springtail is sometimes found in baths and basins, having crawled up drain pipes. This species is most commonly observed in summer when conditions outside are particularly hot and dry, but cooler, moister conditions exist indoors.</p>
<p>Springtails only very rarely become a nuisance, not because they cause allergies or bite, but because they sometimes become extremely numerous in domestic situations. The few records of springtails being found on the human body have almost all been shown to be a case of mistaken identity.</p>
<p>If springtails become too numerous in a house, it is best to use normal cleaning methods, such as vacuuming carpets and sweeping floors to reduce populations. But if the source population is in walls or under floors, this won’t work. </p>
<p>Chemical methods may not be successful as, on the whole, these animals are resistant to pesticides. Instead, the source of the population should be found, which could be pot plant soil, adjacent garden soil, or debris under the floor, and the habitat cleaned out.</p>
<p>Domestic springtails are harmless to us and do not carry diseases. In the natural environment they are considered “goodies” as they are <a href="https://en.wikipedia.org/wiki/Detritivore">detritivores</a> and contribute to nutrient cycling by breaking down organic matter by grazing on microorganisms on dead leaves and in logs.</p>
<p>In the home, therefore, springtails are not to be feared. In the wild, they play a valuable ecological role and many species are colourful and have intriguing habits. </p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/60233/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Penelope Greenslade 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>Springtails are found in every habitat except the oceans.Penelope Greenslade, Honorary Research Fellow, Federation University AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/593792016-05-20T01:10:20Z2016-05-20T01:10:20ZHidden housemates: rats in the ranks<figure><img src="https://images.theconversation.com/files/123291/original/image-20160520-4451-87u0j1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Rats are true natives of our cities. </span> <span class="attribution"><span class="source">Rat image from www.shutterstock.com</span></span></figcaption></figure><p>Rats send shudders down many peoples’ spines, and may in fact be <a href="http://www.theweek.co.uk/72404/david-attenborough-turns-90-six-things-you-didnt-know">Sir David Attenborough’s least favourite animal</a>. But despite their poor reputation, rats are astonishingly successful. </p>
<p>Almost everywhere humans have built their cities, rats have set up their homes – to live with us and off us.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/123290/original/image-20160520-4478-ziwr7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/123290/original/image-20160520-4478-ziwr7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/123290/original/image-20160520-4478-ziwr7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123290/original/image-20160520-4478-ziwr7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123290/original/image-20160520-4478-ziwr7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123290/original/image-20160520-4478-ziwr7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=556&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123290/original/image-20160520-4478-ziwr7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=556&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123290/original/image-20160520-4478-ziwr7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=556&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Black rats are the most common rats in Australia’s cities.</span>
<span class="attribution"><span class="source">Peter Banks</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Know your rodents</h2>
<p>In Australia we have two species of rat that can be considered truly <a href="https://en.wikipedia.org/wiki/Commensalism">commensal</a> - a species that lives off the resources provided by us. </p>
<p>The black rat (<em>Rattus rattus</em>), or ship rat, is the species of rat that people will most often encounter in their houses in Australia. Then there is the brown rat (<em>Rattus norvegicus</em>), also known as the Norway rat (although it doesn’t come from Norway). This is the species that is often kept as pets and used in lab research. </p>
<p>In the northern hemisphere, the much larger brown rats seem to outcompete black rats. But in Australia and New Zealand, <a href="https://www.researchgate.net/profile/Carolyn_King4/publication/230223984_Invasive_European_rats_in_Britain_and_New_Zealand_Same_species_different_outcomes/links/00b7d53c6e91977d3a000000.pdf">black rats are more widespread</a> and common than brown rats, for reasons we don’t fully understand.</p>
<p>Australia also has 60 species of native rodents, including eight species of native <em>Rattus</em> that evolved from from ancestors which arrived about a million years ago. Similar in size to black rats, these native rats have probably prevented the spread of black rats into natural areas, as has happened in New Zealand and Pacific islands which lack native rodents. </p>
<p>It can be hard to tell a black rat from a native bush rat (<em>Rattus fuscipes</em>), but black rats are more slender with longer tails, and bush rats are chubbier. It is easier to pick a brown rat, which is more than twice the size of a black rat. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/123280/original/image-20160519-4475-jlip2e.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/123280/original/image-20160519-4475-jlip2e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/123280/original/image-20160519-4475-jlip2e.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123280/original/image-20160519-4475-jlip2e.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123280/original/image-20160519-4475-jlip2e.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123280/original/image-20160519-4475-jlip2e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=463&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123280/original/image-20160519-4475-jlip2e.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=463&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123280/original/image-20160519-4475-jlip2e.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=463&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Native bush rats are chubbier than their introduced relatives.</span>
<span class="attribution"><span class="source">Peter Banks</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Arrival</h2>
<p>Black rats probably came to Australia <a href="http://publications.rzsnsw.org.au/doi/abs/10.7882/AZ.2011.058">with the First Fleet</a>. There are skeletons of black rats in the gun barrels of sunken Dutch ships off Western Australia, but there is no evidence that their invasion of Australia began before the English landed in Sydney, when they literally jumped ship.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/122807/original/image-20160517-15924-smte5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/122807/original/image-20160517-15924-smte5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/122807/original/image-20160517-15924-smte5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122807/original/image-20160517-15924-smte5e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122807/original/image-20160517-15924-smte5e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122807/original/image-20160517-15924-smte5e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122807/original/image-20160517-15924-smte5e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122807/original/image-20160517-15924-smte5e.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"></a>
<figcaption>
<span class="caption">The first black rat specimens collected in Sydney were mistaken for native rats.</span>
</figcaption>
</figure>
<p>The Macleay Museum at the University of Sydney has the first recorded black rat specimens. These were initially thought to be a native species and given the name <a href="http://www.ecosmagazine.com/paper/EC12344.htm"><em>Hapalotis arboricola</em></a>. In fact, there are loving descriptions of it climbing in local fig trees and <a href="http://www.biodiversitylibrary.org/page/30988090#page/999/mode/1up">entertaining the residents of Mosman</a>. These rats were, however, black rats. They still climb fig trees in Mosman, and are still mistaken for native rodents. </p>
<p>The name black rat is a bit of a misnomer. We have trapped black rats from around Sydney Harbour in many colours, from light fawn, to chestnut brown with white patches, to light grey and sometimes dark grey, and only occasionally black. They can be very cute.</p>
<h2>A very long engagement</h2>
<p>Remains of black rats have been found in Indus civilisations from 4,000 years ago, and even earlier from Israel and the Middle East. They probably originated in India, and are likely to have adapted to human settlement many times in their history. </p>
<p>The black rat is now one of the most widely distributed animals in the world, perhaps only surpassed by humans and house mice. The live on every continent except Antarctica.</p>
<p>What brings them to our houses? The houses we live in provide rats with the secure, thermally stable homes they need to breed in. They eat a vast range of foods, and so can exploit our waste. The urban environments we have created are also relatively free of predators.</p>
<p>When conditions are ideal, black rats can reach very high numbers, giving birth to up to 12 young every five weeks or so. But the urban myths that there is one rat for every person, or that you are never less than six feet from a rat, have <a href="http://www.bbc.com/news/magazine-20716625">little support</a>. In truth, we have no real idea of how many introduced rats there are in Australian cities. </p>
<h2>Unwelcome housemates</h2>
<p>Rats are often unwelcome housemates because of the diseases they spread in their urine and faeces, including leptospirosis (Weil’s disease), salmonella, and <em>E. coli</em>. <a href="https://www.researchgate.net/profile/Dieter_Hochuli/publication/275256855_Are_urban_bandicoots_solely_to_blame_for_tick_concerns/links/558a4cf508ae4e384e261fb1.pdf">They are also hosts of ticks</a> that transmit bacterial infections and induce allergic reactions. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/123289/original/image-20160520-4478-44226c.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/123289/original/image-20160520-4478-44226c.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/123289/original/image-20160520-4478-44226c.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123289/original/image-20160520-4478-44226c.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123289/original/image-20160520-4478-44226c.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123289/original/image-20160520-4478-44226c.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123289/original/image-20160520-4478-44226c.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123289/original/image-20160520-4478-44226c.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Black rats are important carriers of disease.</span>
<span class="attribution"><span class="source">Peter Banks</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Black rats are important hosts of the parasites <em>Toxoplasmosis gondii</em> and rat lungworm - both of which can be fatal to native wildlife and humans. Rats are also famous for carrying the plague, which arrived in Australia in the early 1900s but fortunately died out. Australia remains plague-free.</p>
<p>Rat damage infrastructure when building their nests. They chew electrical cables, increasing the risk of house fires, although why they do this is not clear. </p>
<p>But they actually spend less time in our houses than many people think, more often making use of backyards. They seem especially to love aviaries and hen houses, which provides a ready source of spilled food and underground shelter. </p>
<h2>Aliens, or just wild?</h2>
<p>Just as native rats belong in natural environments, <a href="http://www.publish.csiro.au/?paper=WR15048">cities are rats’ natural habitat</a>. They may be introduced in Australia, but they have evolved in the urban habitats we have imported. </p>
<p>However, black rats can spill over from cities to remnant bushland, entering an environment that has <a href="http://www.publish.csiro.au/?paper=WR15048">not adapted to them</a>. Here they have the potential to <a href="http://publications.rzsnsw.org.au/doi/abs/10.7882/AZ.2011.058">wreak all kinds of havoc</a>.</p>
<p>Black rats are adept climbers and raid birds nests to prey on the eggs of small native birds, which may be one reason why these birds are uncommon in city parks. They also prey on other tree-dwelling wildlife such as <a href="http://rsbl.royalsocietypublishing.org/content/9/3/20121144.short">small bats</a>, skinks and spiders. </p>
<p>In contrast, native bush rats are clumsy climbers, and the type of lungworm carried by native rats doesn’t seem to have the same impact on wildlife and people.</p>
<p>Black rats are aided in this conquest by humans. Almost <a href="http://www.publish.csiro.au/?paper=WR15048">70% of rats living in bushland next to houses have visited those houses sometime in the previous two weeks</a>. This undoubtedly helps to increase rat populations beyond what the natural environmental alone could support. In contrast, native rats rarely visit houses.</p>
<p>So even though black rats are native to our cities, they can still be pests to humans and other wildlife. Killing rats with poison or traps is one option, but the best strategy is to reduce their access to food and shelter. Make sure your neighbours are doing the same, and aren’t providing a refuge for the rats jumping ship from your home. </p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/59379/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Banks receives funding from The Australian Research Council, NSW Office of Environment and Heritage, Taronga Conservation Society Australia, Mosman Council, Rentokil, Bayer, National Parks and Wildlife Service, NZ Ministry of Business, Transport for NSW, The Paddy Pallin Foundation, Manly Council, and The Australian Wildlife Conservancy</span></em></p>Rats have lived with us for thousands of years.Peter Banks, Professor of Conservation Biology, School of Life and Environmental Sciences, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/590722016-05-11T02:57:13Z2016-05-11T02:57:13ZHidden housemates: the mosquitoes that battle for our backyards<figure><img src="https://images.theconversation.com/files/121920/original/image-20160510-20727-10lpoi9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mosquitoes, thousands of mosquitoes! Mosquitoes found in our local wetlands can often overwhelm us but even mosquitoes that have moved into our backyards can cause problems.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>Mosquitoes are <a href="https://www.gatesnotes.com/Health/Most-Lethal-Animal-Mosquito-Week">the most dangerous animals</a> on the planet. They cause no end of anxiety for people at risk of mosquito-borne disease. With the leap of <a href="http://theconversation.com/does-zika-virus-pose-a-threat-to-australia-53557">Zika virus</a> into the international public health spotlight this year, we’re reminded once more how threatening these otherwise fragile insects can be.</p>
<p>But a battle rages in Australian backyards each summer that all too often escapes our attention. There is a fight between the “good” and “bad” mosquitoes for our pot plant saucers and bird baths, our roof gutters and rainwater tanks – and, most importantly, <a href="http://theconversation.com/health-check-why-mosquitoes-seem-to-bite-some-people-more-36425">our blood</a>.</p>
<p>Mosquitoes are incredibly adaptable creatures. They’ve adapted to almost every aquatic environment on the planet, from coastal rockpools to snowmelt streams and polluted drains to pristine wetlands – everywhere, in fact, apart from the open ocean. </p>
<p>Not only will you find mosquitoes in all of these environments, but you’ll find some mosquitoes specifically adapted to these unique habitats. </p>
<p>There is no better example of the adaptability of mosquitoes than in our own backyards.</p>
<h2>Backyard paradise</h2>
<p>There’s a suite of mosquitoes found in tree holes and water-holding plants. They lay eggs at the edges of the small pools of water collected in the nooks and crannies of trees or in leaf axils (the tiny point where the leaf joins the stem). Some mosquitoes have even adapted to life in <a href="https://en.wikipedia.org/wiki/Wyeomyia_smithii">pitcher plants</a>. While many of them are still found in these habitats, others have given up the swamps and forests for our suburbs.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/121996/original/image-20160510-29544-j7n7zb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/121996/original/image-20160510-29544-j7n7zb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/121996/original/image-20160510-29544-j7n7zb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/121996/original/image-20160510-29544-j7n7zb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/121996/original/image-20160510-29544-j7n7zb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/121996/original/image-20160510-29544-j7n7zb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/121996/original/image-20160510-29544-j7n7zb.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">Messy backyards provide opportunities for mosquitoes. Even the smallest collection of water can suite a pest mosquito such as <em>Aedes notoscriptus</em>.</span>
<span class="attribution"><span class="source">Cameron Webb</span></span>
</figcaption>
</figure>
<p>As people intentionally, or unintentionally, started storing water around the home, mosquitoes took the chance to exploit these unoccupied niches. The plastic takeaway food container, the tyre, the bird bath and rainwater tank have all been embraced by mosquitoes, not only as homes but also as a way to hitchhike from one country to another. </p>
<p>There is little doubt that some mosquitoes arrived in Australia for the first time along with European explorers, their eggs hidden away in the cracks and crevices of water barrels. Mosquitoes have kept coming to Australia by air and sea, hidden as eggs on cargo and personal belongings.</p>
<p>The most recent arrival, <em>Aedes albopictus</em>, is <a href="http://theconversation.com/new-mosquito-threats-shift-risks-from-our-swamps-to-our-suburbs-56350">a major cause for concern</a> and may influence <a href="http://theconversation.com/is-climate-change-to-blame-for-outbreaks-of-mosquito-borne-disease-39176">future mosquito-borne disease risk</a>. However, some “home-grown” mosquitoes are already flourishing in our suburbs.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/122012/original/image-20160510-20734-1e2qqj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/122012/original/image-20160510-20734-1e2qqj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/122012/original/image-20160510-20734-1e2qqj9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/122012/original/image-20160510-20734-1e2qqj9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/122012/original/image-20160510-20734-1e2qqj9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/122012/original/image-20160510-20734-1e2qqj9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/122012/original/image-20160510-20734-1e2qqj9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The commonly swatted ‘Aussie backyard mozzie’, <em>Aedes notoscriptus</em>.</span>
<span class="attribution"><span class="source">Stephen Doggett (NSW Health Pathology)</span></span>
</figcaption>
</figure>
<h2>There are “bad” mosquitoes…</h2>
<p>Australia has <a href="http://www.publish.csiro.au/pid/6391.htm">plenty</a> of native mozzies but <em>Aedes notoscriptus</em> probably bites more Australians than any other mosquito. It is widespread across the country, from Darwin to Hobart and from Brisbane to Perth. We’ve even <a href="http://theconversation.com/aussie-mozzie-found-in-urban-california-31784">exported it to California</a>! It is active most of the year, disappearing only in the particularly cold months.</p>
<p>It is found in close association with water-filled containers and water-holding plants (particularly bromeliads). The mosquitoes lay eggs around the edge of the water. Then, as water levels rise, the eggs are covered and the larvae (commonly known as “wrigglers”) quickly hatch out. </p>
<p>It may then take only a week for adult mosquitoes to emerge from the water. They <a href="http://www.bioone.org/doi/full/10.1603/0022-2585%282000%29037%5B0380%3AANDCSA%5D2.0.CO%3B2">don’t fly much more than 200 metres</a> from their favourite habitats. So, if you provide a nicely shaded backyard with plenty of water-holding containers, there isn’t much need for them to move on.</p>
<p>This mosquito is rarely very abundant but it readily bites people. It tends to be more active in the mid- to late afternoon – perfect timing to disrupt backyard activities in the cooler parts of the day. </p>
<p>It has also been <a href="https://jme.oxfordjournals.org/content/35/2/104">implicated in the spread</a> of <a href="http://theconversation.com/explainer-what-is-ross-river-virus-24630">Ross River virus</a>, so it’s more than just an annoying nuisance. It can even infect our pets with <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2915.1996.tb00078.x/abstract;jsessionid=CA41BFE29796AB92DC3DB76BBF546D81.f04t01?">dog heartworm</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/121917/original/image-20160510-20703-fmeanl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/121917/original/image-20160510-20703-fmeanl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/121917/original/image-20160510-20703-fmeanl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/121917/original/image-20160510-20703-fmeanl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/121917/original/image-20160510-20703-fmeanl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/121917/original/image-20160510-20703-fmeanl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/121917/original/image-20160510-20703-fmeanl.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">A photo of the mosquito <em>Toxorhynchites speciosus</em>.</span>
<span class="attribution"><span class="source">Stephen Doggett (NSW Health Pathology)</span></span>
</figcaption>
</figure>
<h2>…but also “good” mosquitoes!</h2>
<p>Pest mosquitoes such as <em>Aedes notoscriptus</em> may be annoying to us, but they’re a delicious treat to one predatory mosquito.</p>
<p><em>Toxorhynchites speciosus</em> is as “good” a mosquito as there can be. First, it is a gorgeous creature. Almost four times the size of a typical mosquito, it is a large dark and shiny mosquito with bright metallic patterns. But they’re not just good-looking.</p>
<p>This is one of the few mosquitoes that don’t need blood. Unlike almost all other mosquitoes, the females of which need blood to develop their eggs, <em>Toxorhynchites speciosus</em> doesn’t bite. </p>
<p>It gets its energy from plant juices and nectar. Its long, curved proboscis is a giveaway to its sugar-feeding lifestyles, and is a friendlier visage than the needle-like proboscis of most other mozzies.</p>
<p>The good news doesn’t end there. Not only are they not pests themselves but the larvae of <em>Toxorhynchites speciosus</em> are predatory and <a href="https://www.youtube.com/watch?v=tYOMbTizqKA">feed on the wrigglers of other mosquitoes</a> found in water-holding containers. In some parts of the world, a closely related mosquito is used as a <a href="http://jinsectscience.oxfordjournals.org/content/15/1/128.abstract">biological control agent</a> of the pests that spread dengue, chikungunya and Zika viruses.</p>
<p>While <em>Toxorhynchites speciosus</em> will chomp through plenty of wrigglers of <em>Aedes notoscriptus</em> each summer in Australian backyards, it is unlikely to make a huge difference in bites. However, next time you see a “giant mozzie” buzz by, think twice before you squish it.</p>
<p>If you want to keep the pest mosquitoes out of your backyard, make sure you get rid of any water-holding containers. If you can’t throw them out, keep them covered.</p>
<p>Check to make sure your roof gutters and drains are clear of leaves and other debris so they flow freely. Check your rainwater tank is screened to stop the mozzies entering. And try not to kill the good guys who help keep the other mozzies at bay!</p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/59072/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 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 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>A war is raging in your backyard between the “good” and “bad” mosquitoes.Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/571042016-04-27T02:03:24Z2016-04-27T02:03:24ZHidden housemates: the termites that eat our homes<figure><img src="https://images.theconversation.com/files/118861/original/image-20160415-11464-1u00er5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">They might be eating your home, but termites play a vital role in ecosystems.</span> <span class="attribution"><span class="source">Termite image from www.shutterstock.com</span></span></figcaption></figure><p>Most of our hidden housemates are harmless. But when it comes to termites, some can literally eat us out of house and home. </p>
<p>While termites’ ability to damage our homes by eating wooden foundations is legendary, most species do not cause problems. Usually they are rarely seen, hidden away inside wood, underground or in their nests. </p>
<h2>The importance of termites</h2>
<p>Termites eat cellulose – the complex sugars that plants use to build leaves, stems and trunks. Cellulose is the <a href="http://link.springer.com/chapter/10.1007%2F978-1-4615-9412-3_6">most abundant organic compound on earth</a>. To find wood and other cellulose sources, termites often construct miniature, private highways under the soil that can radiate more than 50 m from their nests. </p>
<p>Perhaps the most famous termite nests are those made by the magnetic termite, <em>Amitermes meridionalis</em>, in northern Australia. These nests are oriented in a north-south direction. Many other species build mounds of different shapes and sizes, while others nest in wood, underground in the soil, or in trees.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119571/original/image-20160421-7989-mbqc4q.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119571/original/image-20160421-7989-mbqc4q.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119571/original/image-20160421-7989-mbqc4q.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119571/original/image-20160421-7989-mbqc4q.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119571/original/image-20160421-7989-mbqc4q.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119571/original/image-20160421-7989-mbqc4q.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119571/original/image-20160421-7989-mbqc4q.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119571/original/image-20160421-7989-mbqc4q.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 distinctive nests of magnetic termites in northern Australia.</span>
<span class="attribution"><span class="source">Nathan Lo</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The <a href="http://onlinelibrary.wiley.com/doi/10.1029/96GB01893/full">combined mass of termites on earth</a> is estimated at 445 million tonnes, putting them in the top ten alongside cattle, krill, ants and humans. </p>
<p>Outside our homes, termites play a critical role as carbon recyclers and are considered <a href="http://www.publish.csiro.au/pid/154.htm">keystone species</a> in many tropical ecosystems, such as savannah habitats like those of northern Australia, Africa and South America. They use nutrient-rich saliva and gut excretions to build tunnels, which improves the quality of the soil. Alongside ants, there is evidence that <a href="http://www.nature.com/ncomms/journal/v2/n3/full/ncomms1257.html">termites increase crop yields</a>. </p>
<p>When winged adult termites emerge from the nest they become a feast for many animals across the tropics.</p>
<h2>Cockroach relatives</h2>
<p>Termites evolved more than 140 million years ago from social <a href="https://theconversation.com/hidden-housemates-cockroaches-54947">cockroaches</a> that <a href="http://www.sciencedirect.com/science/article/pii/S0960982200005613">burrowed deep into rotting wood</a>. The closest living relatives of termites are <a href="http://www.sciencedirect.com/science/article/pii/S1055790316000427">cockroaches from the genus <em>Cryptocercus</em></a>, found only in isolated mountainous areas of China, Korea and North America. </p>
<p>Mum and dad <em>Cryptocercus</em> pair up and burrow into a large log that will be their home (and source of food) for life. Soon after meeting, the female lays a single clutch of 10 or so offspring, which they both feed and look after for around three years – about half the life of a typical <em>Cryptocercus</em>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119567/original/image-20160421-8007-1khh3vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119567/original/image-20160421-8007-1khh3vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119567/original/image-20160421-8007-1khh3vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119567/original/image-20160421-8007-1khh3vp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119567/original/image-20160421-8007-1khh3vp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119567/original/image-20160421-8007-1khh3vp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119567/original/image-20160421-8007-1khh3vp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119567/original/image-20160421-8007-1khh3vp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=431&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 social cockroach Crypotcercus with its pale young.</span>
<span class="attribution"><span class="source">Dr Christine Nalepa</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>As termites evolved, their firstborn offspring began to look after the next clutch of siblings, freeing mum and dad to produce more sons and daughters. The older siblings stayed to build and defend the colony, and feed and look after the young. </p>
<p>The population of a termite <a href="http://onlinelibrary.wiley.com/store/10.1111/j.1440-6055.1970.tb00766.x/asset/j.1440-6055.1970.tb00766.x.pdf?v=1&t=in9qm0i4&s=509d2370e5a028ed29a13038c083e7f0501bdb85">colony these days can number in the millions</a>. All the offspring derive from of a single reproductive pair (the queen and king). </p>
<p>Some species have evolved alternative systems. Colonies of the Australian termite <em>Nasutitermes exitiosus</em> often contain up to four unrelated pairs living together with their countless offspring in apparent harmony – a bit like a 1960s hippie commune.</p>
<p>In the Japanese termite <em>Reticulitermes speratus</em>, the king tends to outlive the queen. But the <a href="http://science.sciencemag.org/content/323/5922/1687.full">queen produces many half-clones of herself</a> without any genetic input from the king (a form of virgin birth). These clones replace their dead mother, and all mate with the remaining king. In one colony, over 600 of these queen-clones have been found, making it the <a href="http://www.springer.com/gp/book/9789048139767">largest harem known in the animal kingdom</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119572/original/image-20160421-8026-bv0dfe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119572/original/image-20160421-8026-bv0dfe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119572/original/image-20160421-8026-bv0dfe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119572/original/image-20160421-8026-bv0dfe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119572/original/image-20160421-8026-bv0dfe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119572/original/image-20160421-8026-bv0dfe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119572/original/image-20160421-8026-bv0dfe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119572/original/image-20160421-8026-bv0dfe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&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 termite queen (centre) surrounded by workers.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/eyeweed/4918988965/in/photolist-8uF73z-4CnFWF-6bXRbj-8vqRwN-9t6ZoP-8vzyHx-5SzcDW-8vqRz1-ffJZqK-5mgUwE-dXakjQ-awZo5G-awWFhM-4CnG1D-xQa6D-5D2DVD-awZo8C-awZnGG-awZnM7-awWF8X-awWERP-awZnJG-awWEBD-awZob1-awZogq-awZnAu-awWFfg-awWEPc-awWEkD-awWFce-awZnv3-awWEJr-fBgATS-8bV3V5-aib5K6-9wQuSa-fB2hCr-8bV3Kd-dhoNg-awZnDE-ho45cB-awWEEe-7WjJMd-awZodu-7WgsUv-7WgsJa-p8Axb-7WgrMg-7WjHEW-7WjHnC">eyeweed/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<h2>One giant organism</h2>
<p>The vast majority of termite offspring within a colony will never reproduce. Instead, these worker and soldier termites remain in a state of suspended development, never becoming adults. Soldier termites attack predators to ensure the survival of the colony and have evolved impressive jaws or snouts that spray toxic chemicals. </p>
<p>In some species like <em>Neocapritermes taracua</em> from South America, <a href="http://science.sciencemag.org/content/337/6093/436">workers sacrifice themselves</a> through the use of an “explosive backpack”. They do this by rupturing their skin, which allows normally harmless chemicals to mix and produced modified chemicals that are dangerous to any nearby predators.</p>
<p>All the efforts of the workers and soldiers go towards raising a small proportion of their brothers and sisters to adulthood, usually once a year. This select few will grow wings (all four of which are almost identical, hence the scientific name Isoptera meaning “equal wings”), pair up and promulgate the genes they share with their siblings back home.</p>
<h2>Living with us</h2>
<p>The dark, humid areas under the floor of many Australian houses provide the ideal environment for termites to emerge from the soil and create their covered highways up foundations to a mother lode of wooden frames. </p>
<p>In Australia, about <a href="http://www.inspecteast.com.au/TermiteActionVicReport_CMSE_PDF-Standard.pdf">a billion dollars is spent each year</a> on termite control. House-eating termites are <a href="http://www.homebuilders.net.au/pdf/Termite%20Incidence%20Survey%20-%20Termite%20Hazard%20Map.pdf">most common in the tropical north</a>, although they are found throughout the continent. While there are more than 300 species of termite, <a href="http://australianmuseum.net.au/termites-as-pests">only a handful are considered pests</a>. </p>
<p><a href="http://www.homebuilders.net.au/pdf/Termite%20Incidence%20Survey%20-%20Termite%20Hazard%20Map.pdf">Most termites are deterred with chemicals</a> and by replacing damaged wood with treated timber. </p>
<p>Their sophisticated social system is also their Achilles heel. Termite baits contain slow-acting chemicals that prevent termites from moulting or disrupt their nervous systems. Workers voraciously feed on the bait and take it back to the colony, where the poison is spread to the queen, king and their new offspring. </p>
<p>But as one colony is killed, another is often ready to take over. Termites have been around a long time and they are not likely to go away any time soon. </p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/57104/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nathan Lo receives funding from the Australian Research Council.</span></em></p>Termite damage costs Australian homes at least a billion dollars each year – but they are absolutely vital for ecosystems.Nathan Lo, Associate Professor, School of Biological Sciences, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/574782016-04-20T04:22:48Z2016-04-20T04:22:48ZHidden housemates: when possums go bump in the night<figure><img src="https://images.theconversation.com/files/119377/original/image-20160420-25612-tc6ar8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The common brushtail possum has made itself well at home in Australia's cities. </span> <span class="attribution"><span class="source">Possum image from www.shutterstock.com</span></span></figcaption></figure><p>You’re drifting off to sleep when, suddenly, there’s a bump and a thump and an unearthly shriek. But never fear, if your home is making these noises you probably don’t have ghosts, but a family of common brushtail possums. </p>
<p>Researchers have documented 18 different <a href="https://books.google.com.au/books/about/The_Common_Brushtail_Possum_in_South_Aus.html?id=YQQsNAAACAAJ&redir_esc=y">brushtail possum sounds</a>. These include “grunting, growling, hissing, screeching, clicking and teeth-chattering calls, many of which would not be out of place on a horror movie soundtrack”.</p>
<p>Common brushtail possums (<em>Trichosurus vulpecula</em>) live across much of suburban Australia. Although often associated with bushland environments and commonly considered a tree-dweller, these adaptable creatures are also highly attracted to human houses. </p>
<h2>The biggest hidden housemate?</h2>
<p>Despite being the same size as a domestic cat, these lively, nocturnal marsupials frequently make their dens in the ceiling and wall cavities of homes. In fact, <a href="http://www.publish.csiro.au/?paper=WR96092">one study of possums in urban Tasmania</a> found that 87% of their visits to dens were associated with buildings (mostly older houses), while 45% of den visits were to roof cavities. </p>
<p>These hidden animals make themselves known to their human housemates as they run across the ceiling. <a href="http://www.tandfonline.com/doi/full/10.1080/10871200701195928">A Sydney study</a> found that as many as 67% of people whose properties were visited by possums heard possum activity on or in roof cavities, while 58% reported possums living in these spaces. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119381/original/image-20160420-25615-12u2aww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119381/original/image-20160420-25615-12u2aww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119381/original/image-20160420-25615-12u2aww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119381/original/image-20160420-25615-12u2aww.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119381/original/image-20160420-25615-12u2aww.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119381/original/image-20160420-25615-12u2aww.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119381/original/image-20160420-25615-12u2aww.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119381/original/image-20160420-25615-12u2aww.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">A young possum discovers pineapple, via mum.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/wollombi/58499575/in/photolist-6aPTn-9hxWf6-3b5ccP-a9PWRa-5WPxY-6nFeGH-5pXQc-phKXQM-a9SKG3-jVZhcr-a9SLj9-7C2SPE-qBEkbf-ERYf3-tT1bA6-a9PYdz-kxm7J8-eMd26-4LeLPr-aG7nMM-jW1y9A-jVZfzF-e2Rz53-zHiFb-hHTaV-sCzPay-rEkwd-sCzQhd-zgMce-jVZZXF-s5Rnht-jW2HNd-pWbtnQ-jW2Kts-nkaxN-nkatS-ocGWv-i8VQb-jVZQGD-9SzRC-6nasmt-pZwW2Q-9vgtay-hHTcz-hHTbr-3bfemU-3bfdSE-9vdqZp-8T9Bk-mDAKF">Peter Firminger/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Possums in the city</h2>
<p>At the time of European arrival, common brushtail possums were abundant across mainland Australia and Tasmania. However, intensive hunting for a burgeoning fur trade in the 19th and early 20th centuries led to a <a href="http://publications.rzsnsw.org.au/doi/pdf/10.7882/FS.2004.093">drastic decline in possum numbers</a>. Since the end of hunting, habitat degradation and fragmentation, fires and fox predation have put further pressure on possum populations. In contrast, they appear to be <a href="http://www.abc.net.au/science/articles/2006/09/07/2041855.htm">flourishing in our cities</a>. </p>
<p>Common brushtail possums are territorial creatures, usually sleeping alone during the day in dens in tree hollows, rock piles or logs. Dens are often in <a href="http://web.uvic.ca/%7Emclinchy/Web_papers/Johnson_et_al_2001.pdf">limited supply</a> in the bush and possums will compete for nesting sites, sometimes fighting to the death. In contrast, suburbia provides an abundance of potential nesting spaces.</p>
<p>In fact, <a href="http://link.springer.com/article/10.1007%2Fs11252-014-0420-x">urban possums seem to prefer living in human-built structures</a>, even when hollow trees are available. A single roof can provide a home for many cohabiting possums, although disputes among roommates may become raucous. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/119378/original/image-20160420-25592-1tglzav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119378/original/image-20160420-25592-1tglzav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/119378/original/image-20160420-25592-1tglzav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119378/original/image-20160420-25592-1tglzav.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119378/original/image-20160420-25592-1tglzav.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119378/original/image-20160420-25592-1tglzav.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119378/original/image-20160420-25592-1tglzav.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119378/original/image-20160420-25592-1tglzav.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"></a>
<figcaption>
<span class="caption">Abundant food and a broad palate mean people and possums were made for each other.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/wollombi/49941227/">Peter Firminger/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Another reason that brushtail possums have adapted so successfully to our cities is their generalised diet. Unlike specialised eucalypt feeders like the koala, brushtail possums eat the leaves, flowers and fruit of a range of native and exotic plants, as well as Eucalyptus leaves. They also sometimes eat insects and bird eggs. </p>
<p>Thus suburban gardens, with their abundance of fruit trees, roses and vegie patches, provide a “possum supermarket”, conveniently offering a diverse array of tasty, nutritious foods year round – much to the frustration of many gardeners!</p>
<p>In a <a href="http://onlinelibrary.wiley.com/doi/10.1890/08-0940.1/abstract">study in eucalypt woodlands in north Queensland</a>, Jane and her colleagues showed that female possums with access to the greatest amounts of available protein within their home ranges were more likely to breed twice, rather than just once per year.</p>
<p>Eucalypts are generally a poor source of protein and this is likely to limit populations of possums in natural bushland. However, given the abundance of high-quality food sources and limitless den sites in urban environments, it is not surprising that common brushtail possums seem to thrive there.</p>
<h2>A possum in the roof!</h2>
<p>People who share their homes with possums describe hearing them walking around the roof cavity. Emma’s <a href="http://cgj.sagepub.com/content/16/1/29.abstract">research</a> heard residents speak about the “thump, thump, thump” of possums walking across the ceiling. Others described being jolted awake at dawn to crashing and scraping sounds, and a feeling that someone was in the house. Some people admitted thinking their house was haunted, a feeling that was triggered by night-time noises coming from hidden spaces. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/119380/original/image-20160420-25612-144zv9x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/119380/original/image-20160420-25612-144zv9x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/119380/original/image-20160420-25612-144zv9x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/119380/original/image-20160420-25612-144zv9x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/119380/original/image-20160420-25612-144zv9x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/119380/original/image-20160420-25612-144zv9x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=515&fit=crop&dpr=1 754w, https://images.theconversation.com/files/119380/original/image-20160420-25612-144zv9x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=515&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/119380/original/image-20160420-25612-144zv9x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=515&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hello, possum.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/play4smee/2986500020/">play4smee/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p><a href="http://cgj.sagepub.com/content/16/1/29.abstract">Many people enjoy living with possums</a>, because they feel like it connects them to a time before Australia was urbanised. Some people also value personal connections with possums, becoming familiar with the individuals that share their garden – even giving them names and pointing them out to visitors. </p>
<p>However, people also often describe possums as a pest. They complain about the noise and damage that possums can cause. Damage to ceiling cavities, urine stains and odours in the ceiling <a href="http://publications.rzsnsw.org.au/doi/abs/10.7882/FS.2004.093">are reported</a>, and <a href="http://cgj.sagepub.com/content/16/1/29.abstract">some people</a> experience possums dying in the ceiling. These rotting bodies can be overwhelmingly smelly and extremely difficult to find. </p>
<p>It is interesting that many people both value possums and find them to be a pest. This is evidence of the complicated relationship that we have with native animals that live inside our homes. We enjoy their wildness, but are also challenged by the way that they make our homes a little bit less human and a little bit closer to nature. </p>
<h2>Living well with common brushtail possums</h2>
<p>Despite the fact that some people are less keen on house-sharing with possums, they are protected under the wildlife acts of most states in Australia. Although these laws vary, they generally require that residents seek a licence before trapping or moving a possum. </p>
<p>In New South Wales the relevant law is the <a href="http://www.austlii.edu.au/au/legis/nsw/consol_act/npawa1974247/">National Parks and Wildlife Act 1974</a>. If a possum is living in your ceiling, in NSW you can apply to the <a href="http://www.environment.nsw.gov.au/wildlifelicences/CatchandReleasePossums.htm">Office of Environment and Heritage</a> (OEH) for a licence to trap it. Possums must be trapped humanely and released on the property where they were found within 150 m of the place where they were caught. </p>
<p>Note, however: possums moved outside of their home range <a href="http://publications.rzsnsw.org.au/doi/abs/10.7882/FS.2004.093">typically die</a>. They are also usually replaced within four weeks by another possum that moves into their <a href="http://publications.rzsnsw.org.au/doi/abs/10.7882/FS.2004.093">territory</a>. </p>
<p>The OEH suggests that people <a href="http://www.environment.nsw.gov.au/animals/TheBrush-tailedPossum.htm">live alongside possums that share their garden</a>, explaining that “if you encourage a possum to stay around and claim your yard as its territory, other possums will be discouraged from taking up residence”. The OEH also recommends installing nest boxes in trees away from the house to discourage possums from nesting in roofs, and carrying out repairs to <a href="http://www.environment.nsw.gov.au/wildlifelicences/CatchandReleasePossums.htm">close up any holes</a> after possums are removed. </p>
<p>Wildlife protection laws mean that common brushtail possums have a right to live in urban Australia. This means that we need to learn to live well together. </p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/57478/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 organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Grunting, growling, hissing, screeching: if your home is making these noises, you probably have possums.Emma Power, Senior Research Fellow, Geography and Urban Studies, Western Sydney UniversityJane DeGabriel, Research Fellow in Ecology, Hawkesbury Institute for the Environment, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/569842016-04-13T02:59:10Z2016-04-13T02:59:10ZHidden housemates: book-loving silverfish<figure><img src="https://images.theconversation.com/files/117393/original/image-20160404-27129-1yxwmfm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The common grey silverfish, Ctenolepisma longicaudata, in Sydney</span> <span class="attribution"><span class="source">Graeme Smith</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Silverfish belong to <a href="http://anic.ento.csiro.au/INSECTFAMILIES/key_Thysanura-genera.aspx?OrderID=42505&PageID=identify">a group of very primitive insects</a> that were already around before insects developed wings more than 350 million years ago. They changed little over hundreds of millions of years but are now restricted to specific habitats, and some have found a living in our homes. </p>
<p>They are easily recognised by the presence of three tail filaments and the lack of wings. Some species have eyes, others do not; some are covered in dark scales, others in yellowish scales and others lack scales.</p>
<p>There are about 600 species described worldwide but this only scratches the surface. The group as a whole has been very poorly studied. </p>
<p>For example, only 50 native Australian species have been described but probably double this number lie undescribed in museum collections, and most field trips result in the collection of more undescribed than described species.</p>
<h2>Where do they live?</h2>
<p>Silverfish live mainly in three unusual habitats:</p>
<p><strong>Dry leaf litter, the bark of trees, sheltered under rocks.</strong> Silverfish are generally found in the driest material. If there are cockroaches in the leaf litter, it is probably too humid for silverfish. They thrive in hot conditions and are quite common in desert regions. </p>
<p>Most of the family Lepismatidae, including those found in our homes, fall into this category, including one (<em>Thermobia domestica</em>) that prefers the hot dry conditions surrounding ovens in bakeries.</p>
<p><strong>Subterranean.</strong> These eyeless species are found in soil or in caves and recently have been found in deep subterranean habitats (deeper than 20 m) during survey work in holes drilled for iron ore exploration. Most of the family Nicoletiidae are in this category.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117223/original/image-20160403-6825-1xrf5t4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117223/original/image-20160403-6825-1xrf5t4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117223/original/image-20160403-6825-1xrf5t4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=634&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117223/original/image-20160403-6825-1xrf5t4.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=634&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117223/original/image-20160403-6825-1xrf5t4.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=634&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117223/original/image-20160403-6825-1xrf5t4.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=797&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117223/original/image-20160403-6825-1xrf5t4.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=797&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117223/original/image-20160403-6825-1xrf5t4.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=797&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 cave-dwelling silverfish <em>Subtrinemura anemone</em>.</span>
<span class="attribution"><span class="source">Graeme Smith</span></span>
</figcaption>
</figure>
<p><strong>Living with ants or termites.</strong> One subfamily of silverfish has moved into the nests of ants and termites where they apparently feed off refuse in the tunnels or perhaps even steal food from their hosts. They avoid being killed by their hosts through their speed and agility and also probably by the use of disguising pheromones.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117221/original/image-20160403-6820-d4z6dz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117221/original/image-20160403-6820-d4z6dz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117221/original/image-20160403-6820-d4z6dz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=470&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117221/original/image-20160403-6820-d4z6dz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=470&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117221/original/image-20160403-6820-d4z6dz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=470&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117221/original/image-20160403-6820-d4z6dz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=591&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117221/original/image-20160403-6820-d4z6dz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=591&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117221/original/image-20160403-6820-d4z6dz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=591&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 silverfish <em>Australiatelura tasmanica</em> lives in ants’ nests.</span>
<span class="attribution"><span class="source">Graeme Smith</span></span>
</figcaption>
</figure>
<h2>Ancient insects</h2>
<p>Apart from a lack of wings, silverfish have two other primitive traits that distinguish them from their winged cousins.</p>
<p>First, they do not have a final defined adult stage but will continue to moult throughout their life. They reach sexual maturity after about the ninth moult but will continue to moult as many as 50 times during their life.</p>
<p>They mate after moulting so they can lay eggs. They can live for several years, moulting every one to three months depending on temperature and their diet. One advantage of such regular moults is that silverfish can regenerate lost appendages at the following moult, be it a leg or an antenna. </p>
<p>Second, silverfish do not have internal fertilisation. Instead the males and females engage in a mating dance. The male produces a group of threads with a bundle of sperm onto which the female, after suitable encouragement, then sits to take up the spermatozoa.</p>
<h2>Silverfish in the home</h2>
<p>Several species of silverfish have found suitable habitat within our houses, but one of them, the <a href="http://www.cabdirect.org/abstracts/19410500074.html;jsessionid=13C785944B8F45F302F23EBF5F3A3528">grey silverfish</a> (<em>Ctenolepisma longicaudata</em>), predominates in most countries.</p>
<p>This is quite a large silvery-grey species often found in empty bathtubs, and this fact can be explained by two other peculiarities of the family. </p>
<p>First, silverfish do not need to drink. They can absorb moisture from the air – through their rectum! So they are attracted to the bathroom because there is more humidity in the air. </p>
<p>Second, silverfish have quite simple feet of just three claws. They lack the specialised structures that allow other insects to land on smooth surfaces such as glass, so if they fall into the bathtub they just can’t climb out again.</p>
<p>Silverfish used to be very common household pests in Australia in the first half of the 1900s but are declining with the introduction of different household furnishings and cleaning methods. They are basically omnivorous but in houses they prefer starchy materials supplemented with protein from dead insects, insect hairs, fungal spores and pollen, or whatever else they can find. </p>
<p>In our homes they will eat paper, especially old books and the cardboard covering of plasterboard. Wallpaper sizing was often attacked, but wallpaper has gone out of fashion and new glues and sizing compounds are perhaps not so palatable. Silverfish will eat rayon and cotton but not wool, natural silk or fur pelts, unless these have been stored with foodstuff spilled on them.</p>
<p>In general, silverfish are not that important as pests in Australian homes, unless you are a collector of rare books or old photographs. They are slow breeders, and a good spring clean, including seldom disturbed cupboards, will go a long way towards keeping their numbers under control. </p>
<p>If all else fails they are fairly susceptible to most household insecticides and can even be caught in sticky traps baited with rolled oats.</p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/56984/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Graeme Smith receives some funding from Reckitt Benckiser for advice on household insecticide product development, and sometimes funding from environmental survey companies (e.g. Bennelongia, Subterranean Ecology) to identify material collected or describe new species of silverfish.</span></em></p>Silverfish have disappeared from our homes as book-bindings - their favourite food - have improved.Graeme Smith, Phd candidate, Federation University AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/550172016-04-06T05:42:35Z2016-04-06T05:42:35ZHidden housemates: Australia’s huge and hairy huntsman spiders<figure><img src="https://images.theconversation.com/files/116992/original/image-20160331-28445-yucsi6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The social huntsman, _Delena cancerides_, can be found in families of up to 150. </span> <span class="attribution"><span class="source">Linda S. Rayor</span>, <span class="license">Author provided</span></span></figcaption></figure><p>You’re driving along and you open the sun visor. You’re cleaning at home and bump a painting hanging on the wall. Suddenly, out runs a huge, hairy spider. Australia’s huntsman spiders are the stuff of <a href="http://www.buzzfeed.com/jennaguillaume/reasons-the-huntsman-spider-is-your-new-best-friend#.rlGV0JlEDz">myths and nightmares</a>. </p>
<p>But these are also the most interesting of their family and deserve their place in the pantheon of Australian wildlife. </p>
<p>I study the behavioural ecology of these remarkable spiders. Elsewhere in the world I don’t tell people that I study spiders for a living, but I confess that in Australia I do brag a little about being a huntsman specialist.</p>
<p>First, let’s talk numbers: there are currently 1,207 species of huntsman spider in the family Sparassidae, out of the <a href="http://www.wsc.nmbe.ch/statistics/">45,881 described spider species worldwide</a>. It is estimated that 155 huntsman spider species are found throughout Australia. </p>
<p>Of those, approximately 95 species are found only in Australia. All of these are probably descended from a single common ancestor that immigrated from Papua New Guinea or elsewhere in Southeast Asia. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/116999/original/image-20160331-31093-66j88v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116999/original/image-20160331-31093-66j88v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/116999/original/image-20160331-31093-66j88v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116999/original/image-20160331-31093-66j88v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116999/original/image-20160331-31093-66j88v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116999/original/image-20160331-31093-66j88v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116999/original/image-20160331-31093-66j88v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116999/original/image-20160331-31093-66j88v.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">A female <em>Beregama aurea</em>, Australia’s largest huntsman.</span>
<span class="attribution"><span class="source">Linda S. Rayor</span></span>
</figcaption>
</figure>
<h2>Big, and fast</h2>
<p>Huntsmen are big spiders. Australia has a few relatively small species, such as the tiny (non-endemic) and amazingly camouflaged lichen spider, <em>Pandercetes gracilis</em>. But many of the endemics are sizeable animals, which can weigh 1-2 grams and may be as big as the palm of your hand. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/117000/original/image-20160331-6126-11yzh5t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117000/original/image-20160331-6126-11yzh5t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/117000/original/image-20160331-6126-11yzh5t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117000/original/image-20160331-6126-11yzh5t.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117000/original/image-20160331-6126-11yzh5t.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117000/original/image-20160331-6126-11yzh5t.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117000/original/image-20160331-6126-11yzh5t.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117000/original/image-20160331-6126-11yzh5t.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lichen spider, <em>Pandercetes gracilis</em>, from Queensland.</span>
<span class="attribution"><span class="source">Linda S. Rayor</span></span>
</figcaption>
</figure>
<p>The world’s second-largest species, the massive golden huntsman, <em>Beregama aurea</em>, from tropical Queensland, weighs over 5.5 grams. An adult’s forelegs may stretch 15cm and they lay egg sacs the size of golf balls.</p>
<p>Anyone who has chased a leggy huntsman knows that they are exceptionally fast. We have been measuring the running speed of the endemic huntsman species. </p>
<p>The top speed demons are both sizeable animals from tropical Queensland, <em>Holconia hirsuta</em> and <em>Beregama aurea</em>. These run 42 and 31 body lengths per second, respectively. Compare this to the world-record-holding human, Usain Bolt, who runs at a sluggish 5.2 body lengths per second. </p>
<p>These are some of the fastest spiders recorded in the world. The slowpokes, the rotund but colourful badge huntsman (<em>Neosparassus</em> species), run only 16 body lengths per second.</p>
<p>Huntsmen are long-lived for spiders, with most living for about 2.5 years. Although some other primitive spiders (such as tarantulas) can live up to 20 years, most other spiders live less than a year.</p>
<p>All huntsman spiders are active at night, emerging from their retreats to forage for insects and other invertebrates, and occasionally small vertebrates. They are ambush predators, generally sitting and waiting for prey to come close before running and leaping on it. </p>
<p>Huntsmen don’t use webs, but use a combination of vibrations and vision to locate their prey. Consider the huntsman a small workforce of natural insect exterminators in your house and garden.</p>
<p>During the day, most huntsman prefer to rest in retreats under bark, crevices or other protected areas. This is why so many people encounter the spiders under the sun visors of their cars or behind curtains in their homes, because those are perfect tight spaces for a sleepy spider.</p>
<p>Depending on where you live, different huntsman species tend to wander inside. In Canberra, I have no idea where the medium-sized <em>Isopedella pessleri</em> actually live in the wild, because they are most often caught indoors.</p>
<h2>The family that preys together, stays together</h2>
<p>In order to mate with virgin females, male huntsman often search out females that are not quite mature and guard them for long periods. All huntsman females are attentive mothers who actively guard their egg sacs and new-born offspring for around three weeks. For most huntsman species, these are the only social interactions they experience in their entire lives. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/116998/original/image-20160331-28462-1xxedhq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116998/original/image-20160331-28462-1xxedhq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/116998/original/image-20160331-28462-1xxedhq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=522&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116998/original/image-20160331-28462-1xxedhq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=522&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116998/original/image-20160331-28462-1xxedhq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=522&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116998/original/image-20160331-28462-1xxedhq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=655&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116998/original/image-20160331-28462-1xxedhq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=655&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116998/original/image-20160331-28462-1xxedhq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=655&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Holconia insignis adult female guarding an egg sac.</span>
<span class="attribution"><span class="source">Linda S. Rayor</span></span>
</figcaption>
</figure>
<p>But <a href="http://www.pubfacts.com/detail/23831456/A-molecular-phylogeny-of-the-Australian-huntsman-spiders-Sparassidae-Deleninae-implications-for-taxo">the social huntsman, <em>Delena cancerides</em></a>, lives in complex family groups up to 150 strong, led by a dominant matriarch. A single mum establishes a retreat under bark of a dead tree. Her offspring from one to four clutches remain with her until they reach sexual maturity at almost a year old. Peeling off bark to find a family of these spiders can be quite a shock. </p>
<p>These social huntsman aren’t found in our homes, although I’ve heard of them establishing colonies under window shutters. One long-lived colony was in a backyard where the bark retreat had been affixed in place by a laundry line.</p>
<p>Our research shows that having older siblings in the group brings big payoffs to younger animals, as they can <a href="http://www.sciencedirect.com/science/article/pii/S0003347213001371">share prey with their more capable older siblings</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/qB2esLJ58Ko?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Conflict and cooperation in Australian huntsman spiders.</span></figcaption>
</figure>
<p>Why should large spiders remain at home with mum and siblings, when they can clearly fend for themselves? It turns out that there simply aren’t enough suitable under-bark retreats for <em>D. cancerides</em> to occupy. We find that, in most habitats, sufficiently large retreats are rare. </p>
<p>As a result, there is strong competition among <em>D. cancerides</em> for each retreat, and larger females can displace smaller females. We believe that by remaining in the protected shelter of home until they are young adults, the spiders are larger and more competitive in the battle over bark retreats, which are an absolute necessity for raising their own young.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117001/original/image-20160331-15137-1319q7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117001/original/image-20160331-15137-1319q7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117001/original/image-20160331-15137-1319q7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117001/original/image-20160331-15137-1319q7g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117001/original/image-20160331-15137-1319q7g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117001/original/image-20160331-15137-1319q7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117001/original/image-20160331-15137-1319q7g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117001/original/image-20160331-15137-1319q7g.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 social huntsman spiders, <em>Delena cancerides</em>, are found under the bark of dead trees. The mother (on the left) may have four clutches of young who remain with her until they reach sexual maturity. This means that spiders of all sizes interact with each other through their development.</span>
<span class="attribution"><span class="source">Linda S. Rayor</span></span>
</figcaption>
</figure>
<h2>Don’t throw a wobbly and hurt a huntsman</h2>
<p>What should you do if you do find a big spider in your car or living room? First, get a grip! She isn’t going to hurt you. </p>
<p>Second, find a take-away container, scoop the spider into the container and release it outside. Huntsman spiders almost never bite humans since they rely on speed to escape most predators. When they do bite, most bites are quick defensive nips without injecting venom. </p>
<p>In 14 years of studying Aussie huntsman spiders, I’ve handled many thousands of individuals and been bitten only 11 times when I (mostly) deserved it. Their fangs are big enough to break skin, but the venom rarely has much effect.</p>
<p>An exception is the badge huntsman. This is reputed to have a more potent venom, so simply use a container to move them. </p>
<p>Treasure your huntsman spiders. They deserve a place alongside koalas and kangaroos as iconic Australian wildlife.</p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/55017/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr.Linda S. Rayor is affiliated with Cornell University, New York, USA. She was a visiting scholar at ANU from 2002 – 2014</span></em></p>Huntsman spiders deserve a place alongside koalas and kangaroos as iconic Australian wildlife.Linda S. Rayor, Senior Lecturer and Senior Research Associate, Cornell UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/565102016-03-24T00:56:43Z2016-03-24T00:56:43ZHidden housemates: a gecko invasion?<figure><img src="https://images.theconversation.com/files/116700/original/image-20160330-13683-uxh6sb.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A native Australian gecko, Gehyra dubia.</span> <span class="attribution"><span class="source">Eric Vanderduys</span></span></figcaption></figure><p>In northern Australia some houses are filled nightly with chatter. You might hear a distinctive “chuck-chuck-chuck”, or find calling cards (droppings) on skirting boards, picture frames and window sills. If so, you probably have gecko housemates. </p>
<p>If you live anywhere from Brisbane to Broome, it is likely your house is home to two very similar species, the introduced Asian House Gecko (<em>Hemidactylus frenatus</em>) and one of several species of native Australian counterparts, the dtellas (<em>Gehyra sp.</em>).</p>
<p>Other native species you might see around your house include the velvet geckos (<em>Oedura sp</em>), while other introduced species include the Mourning Gecko (<em>Lepidodactylus lugubris</em>).</p>
<p>As nocturnal reptiles, geckos generally hide during the day and emerge at night. The species we see around our homes are taking advantage of the insect-attracting lights that fill our cities and towns. These provide an endless smorgasbord of food for the geckos.</p>
<p>Asian House Geckos established themselves in Darwin in the 1960s. It is most likely they travelled here as stowaways in cargo ships. Since then their distribution has expanded along transport routes. They are now found along the northern and eastern coasts, most commonly around buildings or other manmade structures. </p>
<h2>Who are your gecko housemates?</h2>
<p>Check a reptile field guide to see which geckos are in your area. Most of them can be identified fairly easily, but if you live with Asian House Geckos (<em>Hemidactylus frenatus</em>) and dtellas (species of <em>Gehyra</em>) you will need to pay extra attention. </p>
<p>The following tips will help you tell your <em>Hemidactylus</em> from your <em>Gehyra</em>:</p>
<ul>
<li>Looks: Both species are similar in size, about 11 cm total body length, and are pinkish-brown to dark grey with velvety skin and large eyes. If you look closely, the Asian House Geckos have spines on either side of their tail. Each of their toes has claws. Dtellas, on the other hand, are spineless. They have claws on their outer toes but the toe closest to their body is clawless.</li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/116122/original/image-20160323-32312-3b8r9e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116122/original/image-20160323-32312-3b8r9e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/116122/original/image-20160323-32312-3b8r9e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116122/original/image-20160323-32312-3b8r9e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116122/original/image-20160323-32312-3b8r9e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116122/original/image-20160323-32312-3b8r9e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116122/original/image-20160323-32312-3b8r9e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116122/original/image-20160323-32312-3b8r9e.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 Asian House Gecko arrived in Australia in the ‘60s. If you look closely, you can see spines running down its tail.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/magdalena_b/5567730558/in/photolist-fNjuGE-g5L496-9u15js-g5K5Gv-5x5zbR-6GnQCQ-9u14oh">magdalena_b/Flickr</a></span>
</figcaption>
</figure>
<ul>
<li><p>Call: Asian House Geckos are much louder and more talkative than natives; their “chuk-chuk-chuk” is sometimes described as “scolding”, whereas native geckos tend to chatter very softly.</p></li>
<li><p>Eggs: Both Asian House Geckos and native geckos lay one or two eggs that are round, hard-shelled and resistant to moisture loss. </p></li>
</ul>
<h2>Who rules the house?</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/116124/original/image-20160323-32323-1xhojm3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116124/original/image-20160323-32323-1xhojm3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/116124/original/image-20160323-32323-1xhojm3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=906&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116124/original/image-20160323-32323-1xhojm3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=906&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116124/original/image-20160323-32323-1xhojm3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=906&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116124/original/image-20160323-32323-1xhojm3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1139&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116124/original/image-20160323-32323-1xhojm3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1139&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116124/original/image-20160323-32323-1xhojm3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1139&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An intrepid gecko’s eggs laid in a keyhole.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/yeled/86799048/in/photolist-8EScz-8ESkj-fp5qyQ-8ES6E-CayXqJ-bYv29w-6hc4SM">Charlie Allom/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Are introduced geckos pushing out our native species? While they have been <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1442-9993.2010.02143.x/full">implicated in the exclusion of native house geckos</a>, the extent of this is unknown. </p>
<p>One theory is that the hunting style of the Asian House Gecko gives them an advantage under bright city lights. These geckos are active hunters and can feed efficiently where insects congregate around artificial light. Native geckos, on the other hand, seem to forage where prey is more dispersed. </p>
<p>Indeed, <a href="http://onlinelibrary.wiley.com/doi/10.1111/aec.12287/full">Asian House Geckos are willing to use more brightly lit areas</a>, whereas natives choose darker areas. </p>
<p>While Asian House Geckos may have access to more insects in light areas, it’s possible that some native species and the house gecko are exploiting different parts of the “house gecko niche” and happily living together.</p>
<h2>Geckos in the bush</h2>
<p>Asian House Geckos have been recorded in natural habitats away from our homes. Could they invade native bushland?</p>
<p>On various islands of the Pacific and Indian oceans, introduced Asian House Geckos displace resident geckos from the house-gecko niche and have managed to spread beyond areas of human habitation. Most notably, in the Mascarene Islands, <a href="http://www.sciencedirect.com/science/article/pii/S0006320705001850">Asian House Geckos have invaded all natural habitats</a>. This has led to the decline of the native <em>Nactus</em> gecko populations and the extinction of three species.</p>
<p>But <a href="http://www.publish.csiro.au/?paper=ZO12077">perhaps this is not the case in Australia</a>. Surveys conducted across northern Australia failed to find evidence that Asian House Geckos were successfully invading natural habitats. Based on this study, it seems this species will continue to thrive with people but is unlikely to spread further. More research is underway to investigate if Asian House Geckos are invading the bush in different parts of their range.</p>
<p>Scientists agree, however, that novel parasites and pathogens carried by Asian House Geckos could pose a threat to Australian wildlife. We don’t know, but it’s definitely something to watch.</p>
<p>Next time you come across your gecko housemates, take a closer look. Are you harbouring native species, or a potential invader?</p>
<p><em>Correction: the lead image on this article was corrected on March 30 2016. The original image was incorrectly described as a native gecko.</em></p><img src="https://counter.theconversation.com/content/56510/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lin Schwarzkopf receives funding from the Australian Research Council, and Meat and Livestock Australia. </span></em></p><p class="fine-print"><em><span>Heather Neilly 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>If you’re hearing a strange chatter in your home, you may have gecko housemates.Heather Neilly, PhD Candidate, Centre for Tropical Biodiversity and Climate Change Navigation, James Cook UniversityLin Schwarzkopf, Professor in Zoology, James Cook UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/549472016-03-17T03:26:24Z2016-03-17T03:26:24ZHidden housemates: cockroaches<figure><img src="https://images.theconversation.com/files/115352/original/image-20160316-30241-sy2cd5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The American Cockroach, one of the most common species found in your home.</span> <span class="attribution"><span class="source">Cockroach image from www.shutterstock.com</span></span></figcaption></figure><p><a href="http://palaios.geoscienceworld.org/content/18/3/256.abstract">Cockroaches are a very ancient group of insects</a>. They have been around virtually unchanged in general appearance since the Carboniferous period, more than 300 million years ago.</p>
<p>Technically speaking they are in the Order Blattodea (the same level of classification as, for instance, all butterflies and moths). <a href="http://rsbl.royalsocietypublishing.org/content/3/3/331">Cockroaches are very closely related to termites</a>; in fact, some recent work suggests they should be grouped together.</p>
<p>Australia has about <a href="http://australianmuseum.net.au/native-cockroaches">400 species of cockroach</a>, none of which make it to pest status of any note. </p>
<p>But others have made their living inside our homes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/115353/original/image-20160316-30241-165fy9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/115353/original/image-20160316-30241-165fy9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/115353/original/image-20160316-30241-165fy9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/115353/original/image-20160316-30241-165fy9w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/115353/original/image-20160316-30241-165fy9w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/115353/original/image-20160316-30241-165fy9w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=457&fit=crop&dpr=1 754w, https://images.theconversation.com/files/115353/original/image-20160316-30241-165fy9w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=457&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/115353/original/image-20160316-30241-165fy9w.jpg?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"></a>
<figcaption>
<span class="caption">The rather handsome Speckled Cockroach from north-east Africa has spread across the world with human assistance.</span>
<span class="attribution"><span class="source">Anthony O'Toole</span></span>
</figcaption>
</figure>
<h2>Cockroach 101</h2>
<p>Cockroaches are social insects and often live in family groups. They have unusual reproduction: females lay eggs in groups of 4-30 bundled together. It looks like one big egg, but is actually many small eggs encased together in what is called an ootheca. Some species retain their egg(s) and <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1440-6055.1984.tb01922.x/abstract">give birth to live nymphs</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/115354/original/image-20160316-30237-15bjwes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/115354/original/image-20160316-30237-15bjwes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/115354/original/image-20160316-30237-15bjwes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=526&fit=crop&dpr=1 600w, https://images.theconversation.com/files/115354/original/image-20160316-30237-15bjwes.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=526&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/115354/original/image-20160316-30237-15bjwes.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=526&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/115354/original/image-20160316-30237-15bjwes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=660&fit=crop&dpr=1 754w, https://images.theconversation.com/files/115354/original/image-20160316-30237-15bjwes.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=660&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/115354/original/image-20160316-30237-15bjwes.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=660&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cockroach eggs are bundled together in an ‘ootheca’.</span>
<span class="attribution"><span class="source">Anthony O'Toole</span></span>
</figcaption>
</figure>
<p>Once the egg hatches the cockroach develops through several nymphal stages before moulting to the adult stage. Immediately after moulting a cockroach may appear almost a “ghostly” pale white or cream colour, before its cuticle or exoskeleton develops its characteristic tanned appearance.</p>
<p>Development is relatively rapid: 30-40 days from egg to the adult stage. Adults of some species can live for up to a year and reproduce many times. Thus, from a single colonising egg-bearing female, a large population or infestation can develop in a relatively short time.</p>
<p>Cockroaches feed on a variety of substances that contain cellulose, starch, sugars and associated micro-organisms: from decaying wood to sewage. They can go without food, but not water, for a long time. They tend to hang out in damp or moist places.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/115355/original/image-20160316-30227-1n8ia8u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/115355/original/image-20160316-30227-1n8ia8u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/115355/original/image-20160316-30227-1n8ia8u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/115355/original/image-20160316-30227-1n8ia8u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/115355/original/image-20160316-30227-1n8ia8u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/115355/original/image-20160316-30227-1n8ia8u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=473&fit=crop&dpr=1 754w, https://images.theconversation.com/files/115355/original/image-20160316-30227-1n8ia8u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=473&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/115355/original/image-20160316-30227-1n8ia8u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=473&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 nymph of a Speckled Cockroach.</span>
<span class="attribution"><span class="source">Anthony O'Toole</span></span>
</figcaption>
</figure>
<h2>In your home</h2>
<p>Cockroaches are considered a pest because they can contaminate food and kitchen utensils with their frass (droppings), <a href="http://trove.nla.gov.au/work/9722103">possibly spreading microbes and causing health problems</a>. Some people may be allergic to cockroaches, or their byproducts, and many people dislike their appearance. Large infestations can result in an unpleasant smell.</p>
<p>There are about 5,000 species of cockroach but only a handful make it to “pest” status, mainly because they make a living in houses.</p>
<p>Two species that are most likely to be found in your home are both are “ring-ins”: the American Cockroach, <em>Periplaneta americana</em>, and the German Cockroach, <em>Blattella germanica</em>.</p>
<p>The German Cockroach is perhaps the most feared due to its high reproductive potential – one female can give rise to more than 10 million individuals in one year (three to four generations) – and the fact that they are believed to mechanically transmit disease. This species has a very broad dietary range.</p>
<p>The American Cockroach is commonly found in sewer systems. Other species that can be found co-habiting with humans are the Brown-banded Cockroach (<em>Supella longipalpa</em>) and the Oriental Cockroach (<em>Blatta orientalis</em>).</p>
<p>If you are seeing cockroaches outside the kitchen area and during the day you have a major problem or at least a significant infestation.</p>
<p>Control is possible, but elimination is not – or, at least, not without poisoning yourself! Strict hygiene is essential. This will greatly help but not eliminate them – pay particular attention to scrap bins, rubbish bins and drains, as well as benchtops and floors.</p>
<p>Electronic insect “repellers” do not work. Pyrethrum surface spray, a natural insecticide, applied along skirting boards can help – cockroaches tend to move along edges.</p>
<p>In cases with severe infestations it is best to contact local control professionals.</p>
<p>The idea that cockroaches are indestructible is simply an artefact of them being difficult to eliminate. They develop resistance to insecticides, as do nearly all insects if targeted. They have remained relatively unchanged for hundreds of millions of years and survived great extinction events.</p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/54947/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Myron Zalucki 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>There are over 5,000 species of cockroach, but fortunately only a few have chosen to live with us.Myron Zalucki, Professor School of Biological Sciences, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/555702016-03-09T02:02:49Z2016-03-09T02:02:49ZHidden housemates: the Australian redback spider<figure><img src="https://images.theconversation.com/files/114233/original/image-20160308-15341-1ggxrjh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Latrodectus hasseltii, the redback spider. </span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Latrodectus_hasseltii.jpg">Toby Hudson/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Australia is infamous for its <a href="http://www.australiangeographic.com.au/topics/wildlife/2013/03/australias-dangerous-animals-the-top-30/">deadly snakes, spiders and sea creatures</a>. One of the most notoriously dangerous is the redback spider, <em>Latrodectus hasselti</em>, which is similar to the widow spiders found in the United States and worldwide. </p>
<p>What makes these creatures so feared is a combination of their potent venom and their preference for living near people. </p>
<p>But are these spiders really as bad as they seem? And what should we be aware of to minimise the risks of living with these hidden housemates? </p>
<h2>How to recognise a redback</h2>
<p>The female redback is immediately recognisable by the prominent long red stripe on her back, for which they are so aptly named. Females of the species tend to be larger than the males, with a body length of about 1 cm compared to 3–4 mm for males. </p>
<p>Adult females are jet black (with a red stripe), whereas juvenile females are generally brown with white markings. Males are normally light brown with white markings, but lack the distinctive red stripe. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=432&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=432&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=432&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=543&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=543&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114206/original/image-20160308-15308-128ge6u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=543&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Female redback spider (<em>Latrodectus hasselti</em>).</span>
<span class="attribution"><span class="source">Laurence Grayson/Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>One unique feature of redbacks’ mating is “<a href="https://www.youtube.com/watch?v=fgqGAvG-BZ8">sexual cannibalism</a>”. During mating, not only does the female eat the male, but the male actually assists her in this process by flipping his body towards her so that he is closer to her mouthparts. Because the cannibalistic process is so slow, mating continues until the male succumbs to his injuries.</p>
<p>While it may seem counter-intuitive, this is thought to increase his chances of producing offspring by fertilising more eggs (mating is prolonged while the female is devouring the male). She is more likely to reject subsequent male attention. Males also can’t produce any more sperm. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/fgqGAvG-BZ8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Redback spiders are found throughout Australia. They live anywhere with an adequate food supply, shelter and a warm enough climate for breeding. For the most part nocturnal, they use a web to capture prey (generally insects, although they have been known to eat other spiders and even small reptiles and mammals). </p>
<p>They use their venom to kill their prey following capture. Of the hundreds of compounds in their venom, only a single toxin, alpha-latrotoxin, is responsible for deaths in humans and other vertebrates.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114221/original/image-20160308-15323-1cgai8p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&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 redback spider with a small lizard captured in its web.</span>
<span class="attribution"><span class="source">Calistemon/Wikimedia Commons</span></span>
</figcaption>
</figure>
<h2>Interactions with humans</h2>
<p>No matter how deadly an animal is, if it never meets a human it can never kill one. </p>
<p>Unfortunately, this is not the case for redbacks. Existing in a range of habitats from forest to desert (originating in Western Australia), the redback spider quickly took advantage of man-made habitats created by European settlers from the late 18th century onwards. Redbacks had colonised urban areas by the early 1900s. </p>
<p>Insects, their natural prey, are drawn to lights and waste. This makes urban areas an ideal hunting ground for the spiders.</p>
<p>Modern-day redback spiders rely on humans. A quick glance at the distribution of redbacks in Australia reveals it correlates well with populated areas. The spiders are most often found in or around human homes, with only a small proportion located outside urban areas. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=532&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=532&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=532&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=669&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=669&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114203/original/image-20160308-15291-1dzib5q.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=669&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Distribution map of redback spider specimen records.</span>
<span class="attribution"><span class="source">Atlas of Living Australia</span></span>
</figcaption>
</figure>
<p>This attraction to man-made habitats has facilitated the redback’s spread to other countries through world trade and global shipping. </p>
<p>In fact, the redback was unintentionally introduced, and has since established local colonies, in places including <a href="http://www.nzherald.co.nz/rotorua-daily-post/news/article.cfm?c_id=1503438&objectid=11396295">New Zealand</a>, the <a href="http://gulfnews.com/news/uae/environment/redback-spiders-are-back-don-t-panic-urges-dubai-municipality-1.1155440">United Arab Emirates</a>, the <a href="http://www.mirror.co.uk/news/uk-news/deadly-spider-can-kill-one-4715326">United Kingdom</a> and <a href="http://news.xinhuanet.com/english/health/2012-12/26/c_132065195.htm">Japan</a>. </p>
<p>New Zealand quarantine authorities commonly intercept the spiders in steel or car shipments. Any unintentional introduction is of concern both for local people, who may be <a href="http://www.dailystar.co.uk/news/latest-news/395595/Redback-spider-bite-kills-dad-of-five-Ireland">unaware of the spider’s dangerous bite</a>, and for the preservation of insects on which the redback would not normally have an opportunity to prey. </p>
<h2>How dangerous are they?</h2>
<p>The majority of reported spider bites in Australia are attributed to redbacks, which are responsible for around 2,000 hospitalised bite cases each year. However, not a single death due to redback venom has been reported for 50 years, since the introduction of redback antivenom.</p>
<p>Redback spiders tend not to be aggressive unless their web is disturbed.
Sometimes they may just give a warning bite without injecting any venom if they feel threatened. </p>
<p>Therefore, not every bite will require a trip to the hospital or treatment with antivenom. In fact, antivenom is normally given only in cases in which the injected venom has caused severe illness. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114226/original/image-20160308-15344-14kuage.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">Bite from a Latrodectus spider.</span>
<span class="attribution"><span class="source">David~O/flickr</span></span>
</figcaption>
</figure>
<p>When the redback venom enters the body, it produces a range of effects collectively referred to as “<a href="https://en.wikipedia.org/wiki/Latrodectism">latrodectism</a>”. Typically this includes severe and escalating pain that emanates and progresses from the bite site, swelling and localised sweating. Nausea, vomiting, headaches, abdominal or chest pain, generalised sweating and increased blood pressure indicate a severe bite. Symptoms of latrodectism usually last for 24 to 48 hours, but can persist for weeks in some cases.</p>
<p>Nearly all instances are ascribed to the larger female spider. Both the juvenile and adult produce physical symptoms of similar severity. Bites from the smaller males are reported to give only mild, short-lived pain.</p>
<h2>What we can do to live safely with them</h2>
<p>Keeping in mind that redback spiders are not generally aggressive unless disturbed, following a few simple precautionary measures greatly reduces the risk of being bitten. </p>
<p>Webs are normally found in dark, dry, sheltered spaces. Be careful around buildings, under houses, in roofs and in sheds and garages. Always check first before reaching into your mailbox or other dark holes. </p>
<p>Check around children’s sandpits, toys and bicycles, inside helmets or any other equipment that gets left outside. Before use, always shake out any clothes, shoes, gloves or garden tools that have been left outside. </p>
<p>When gardening, wear gloves and shoes. Be careful when disposing of rubbish or litter piles. Inactive cars are also great places for redbacks to build webs. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=639&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=639&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=639&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=803&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=803&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114219/original/image-20160308-15328-78vkzf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=803&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 redback spider in a corner of a household deck.</span>
<span class="attribution"><span class="source">Charles Haynes/flickr</span></span>
</figcaption>
</figure>
<p>Be extra observant in warmer months, particularly in the late afternoon and evening, when the spiders are most active. Children should also be taught not to touch spiders. </p>
<p>If you find a redback or a redback egg sac and want to get rid of it, the easiest way is to squash it with something like a rolled-up newspaper, but only if you think it is safe to do so. Pesticides are not very effective in the long term unless used frequently, because redbacks will generally recolonise after treatment.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114205/original/image-20160308-15338-124ppcu.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">Female redback with egg sac and prey (a blowfly).</span>
<span class="attribution"><span class="source">Fir0002/Flagstaffotos</span></span>
</figcaption>
</figure>
<p>If you do get bitten, don’t panic. For healthy people, a redback bite is not an immediate emergency. It is advisable to have someone stay with you and observe you for a few hours, in case severe symptoms develop, so that they can get you to a hospital. </p>
<p>Doctors can then monitor your situation and, if necessary, administer the antivenom. People with serious medical conditions (particularly heart disease), pregnant women, children or the elderly are at a much greater risk of severe, and potentially fatal, effects or complications. They should be monitored at hospital. </p>
<p>In any situation, if in doubt, seek medical attention.</p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/55570/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Natalie J. Saez 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>Be thankful you aren’t a male redback spider.Natalie J. Saez, Research officer, Institute for Molecular Bioscience, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/548012016-03-02T02:03:54Z2016-03-02T02:03:54ZHidden housemates: we live with a zoo of harmless mini-beasts<figure><img src="https://images.theconversation.com/files/113487/original/image-20160302-25881-1ks9mx8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fungus gnats are one the many arthropods that find their way into our homes. </span> <span class="attribution"><span class="source">Gnat image from www.shutterstock.com</span></span></figcaption></figure><p>Do you take pride in a clean house? They may not be obvious, but a <a href="http://news.nationalgeographic.com/2016/01/160119-insects-spiders-bugs-homes-science-animals/">recent US survey</a> has shown that each of our homes harbours a fauna of perhaps hundreds of species of insect and other terrestrial arthropods such as mites, millipedes and centipedes. </p>
<p>The survey, conducted in free-standing houses in Raleigh, North Carolina, sampled every arthropod, both known pests and others. Almost 75% of the diversity consisted of just four main groups, true flies (Diptera), spiders (Araneae), beetles (Coleoptera), and wasps and ants (Hymenoptera). </p>
<p>Most of the species are not the ones you might traditionally associate with houses, such as German cockroaches (<em>Blattella germanica</em>) and house flies (<em>Musca domestica</em>), but rather tended to be local arthropods filtered from the surrounding landscape. </p>
<p>More than 500 rooms were surveyed in total, and a staggering 99% of them contained arthropods. Insects were overwhelmingly common, with over 90% of kitchens, bedrooms and bathrooms harbouring them. The bigger the house, the more species it contained, and the human inhabitants were generally unaware of their uninvited guests. </p>
<p>How do these insects enter homes? As in Australia, most US homes have fly screens installed on windows, but many of these arthropods are small and can enter through the gaps around doors and windows, chimneys, drains, basements, attics and ceiling spaces. </p>
<p>Although no similar study has been done in Australia, it would probably uncover similar results. So what are all these mini-beasts doing in our homes?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/113470/original/image-20160301-12114-v84caq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113470/original/image-20160301-12114-v84caq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/113470/original/image-20160301-12114-v84caq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=513&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113470/original/image-20160301-12114-v84caq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=513&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113470/original/image-20160301-12114-v84caq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=513&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113470/original/image-20160301-12114-v84caq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=645&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113470/original/image-20160301-12114-v84caq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=645&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113470/original/image-20160301-12114-v84caq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=645&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Proportion of different arthropods found in homes: there are a lot of flies and spiders.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.7717/peerj.1582">Bertone et al</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Meet the arthropods</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/113474/original/image-20160302-12131-1qtvroo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113474/original/image-20160302-12131-1qtvroo.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/113474/original/image-20160302-12131-1qtvroo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1314&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113474/original/image-20160302-12131-1qtvroo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1314&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113474/original/image-20160302-12131-1qtvroo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1314&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113474/original/image-20160302-12131-1qtvroo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1651&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113474/original/image-20160302-12131-1qtvroo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1651&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113474/original/image-20160302-12131-1qtvroo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1651&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 most common mini-beasts in homes: (A) cobweb spiders (B) carpet beetles (C) gall midges (D) ants (E) book lice (F) dark-winged fungus gnats (G) cellar spiders (H) weevils (I) mosquitoes (J) scuttle flies (K) leafhoppers (L) non-biting midges.</span>
<span class="attribution"><a class="source" href="https://peerj.com/articles/1582/">Bertone et al</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Arthropods have been living in our homes ever since we moved out of caves and built houses. For example, the remains of a variety of <a href="http://www.sciencedirect.com/science/article/pii/S0305440301906971">beetles that consume grains are common in Egyptian archaeological sites more than 3,000 years old</a>. </p>
<p>Animal domestication and food storage brought many different opportunities for arthropods to make a living where we live. Some, such as bed bugs, may have <a href="http://link.springer.com/article/10.1007%2Fs00436-012-2862-5">followed us out of the caves</a>. </p>
<p>Most studies have focused on known pests, with particular emphasis on medically and economically important species such as mosquitoes, termites, fleas and dust mites. </p>
<p>The US study was the first to uncover the multitude of other non-pest species in our homes. Their true interactions with humans remain largely unknown. None is known to cause us any direct harm.</p>
<p>Common groups found in almost all houses included cobweb spiders (Theridiidae), carpet beetles (Dermestidae), gall midges (Cecidomyiidae), ants, book lice (Liposcelididae), and fungus gnats (Sciaridae). Dust mites and American cockroaches were found in 75% of the houses sampled. Flies were found in over 80% of homes, but the commonest ones (non-biting midges, Chironomidae; and gall midges, Cecidomyiidae) are harmless and form part of the aerial plankton outside homes.</p>
<p>Interestingly, none of the homes surveyed had any bed bugs. This suggests these insects may thrive best in motels, hotels and hostels rather than in permanent residences.</p>
<p><a href="http://jee.oxfordjournals.org/content/107/2/867">Book lice have a broad diet</a>, including grain, fungi, paper products and organic waste, and have a long history of living in close association with birds and mammals and their nests. They can survive for long periods without food and females can reproduce without sex (parthenogenesis). Both these attributes contribute to their success. </p>
<h2>A whole ecosystem in your living room</h2>
<p>The insects found have a range of different relationships with people, from species that have a very strong association (for example, carpet beetles, cobweb spiders), to others that seek shelter and resources only occasionally (ants, hunting spiders), to others that blunder into our homes and are trapped to their detriment (plant-feeding bugs and gall midges).</p>
<p>Many of the insects found were plant feeders. The were probably attracted into the home by lights at night, or introduced via cut flowers, and cannot complete their life cycle in the home. </p>
<p>Some, such as the fungus gnats (Sciaridae), may be able to complete their life cycle in the soil associated with indoor plants. Some predators, such as spiders, are able to feed on other arthropods in the home, and others are tiny parasitic wasps, which may be able to complete their life cycle on other arthropods in the home. </p>
<p>In these cases our homes may contain very simple, but self-sustaining, ecosystems. </p>
<p>Many of the insects found in the US homes are a sample of the local arthropod fauna that are not known to cause us any direct harm. All the pest groups in the US homes are also present in Australia and elsewhere. </p>
<p>These results suggests that if a similar survey was conducted in an Australian city, a minority of the insects would be the cosmopolitan pests found in human houses all over the world, whereas the majority would be a sample of the local Australian arthropod fauna. </p>
<p>Should we be worried? Probably not - other recent research has shown <a href="http://link.springer.com/article/10.1007%2Fs11252-007-0045-4">how diverse the arthropod fauna is in urban areas</a> as well. If your home harbours a healthy arthropod fauna, it is safe for you as well. Whether we like it or not, we have evolved with a zoo of arthropod mini-beasts in our dwellings and suburbs for millions of years. </p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a>.</em></p><img src="https://counter.theconversation.com/content/54801/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Yeates 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>Our homes harbour hundreds of species of insects and their relatives.David Yeates, Director of the Australian National Insect Collection, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/549002016-02-23T19:04:54Z2016-02-23T19:04:54ZHidden housemates: big fleas, and their little fleas<figure><img src="https://images.theconversation.com/files/112309/original/image-20160222-25855-1djjhcn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The cat flea (Ctenocephalides felis) female full of eggs</span> <span class="attribution"><span class="source">Jan Slapeta</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Itchy? Maybe not, but your cat or dog might be. If you live in any of the major coastal cities in Australia, you are no stranger to a scratching dog or cat. You can blame fleas, or more specifically their bites and saliva, to which your pet is hypersensitive.</p>
<h2>Did <em>T. rex</em> have fleas?</h2>
<p>Fleas are marvellous creatures! They are <a href="https://en.wikipedia.org/wiki/Parasitism#Types">ectoparasites (parasites that live outside their hosts’ bodies)</a>, exploiting their hosts both by using them for nutrition and to stay well protected from the harsh outside environment beyond their host’s fur. </p>
<p>Big fleas even have little “fleas” of their own as well, but more on that a little later. I borrowed the headline from a book by <a href="https://books.google.com.au/books?id=MpnwAAAAMAAJ&q">Robert Hegner</a>, who in 1938 used superb illustrations and narratives to explain the world of parasitology. This in turn is perhaps derived from <a href="https://en.wikipedia.org/wiki/The_Siphonaptera">the nursery rhyme, The Siphonaptera</a> (the group of insects to which fleas belong):</p>
<blockquote>
<p>Big fleas have little fleas,
<br>Upon their backs to bite ‘em,
<br>And little fleas have lesser fleas,
<br>and so, ad infinitum.</p>
</blockquote>
<p>There are about 80 different flea species in Australia and more than 2,000 globally. Even birds have their fleas, and because <a href="https://theconversation.com/book-review-flying-dinosaurs-how-fearsome-reptiles-became-birds-30704">birds are essentially dinosaurs</a>, I pose the question: was <em>Tyrannosaurus rex</em> feeling that flea bite, too?</p>
<h2>When did fleas start living with us?</h2>
<p>The dog is man’s closest companion and the cheeky cat a close second. When this relationship was forged, and up until very recently, we shared our human fleas with the dogs and cats, and <em>vice versa</em>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/112454/original/image-20160223-25876-tody35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/112454/original/image-20160223-25876-tody35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/112454/original/image-20160223-25876-tody35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/112454/original/image-20160223-25876-tody35.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/112454/original/image-20160223-25876-tody35.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/112454/original/image-20160223-25876-tody35.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=388&fit=crop&dpr=1 754w, https://images.theconversation.com/files/112454/original/image-20160223-25876-tody35.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=388&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/112454/original/image-20160223-25876-tody35.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=388&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Human flea male and female (Pulex irritans)</span>
<span class="attribution"><span class="source">Jan Slapeta</span></span>
</figcaption>
</figure>
<p>With better sanitation and improved housing conditions, the human flea has essentially disappeared from Australia. This left a duel between the cat flea and the dog flea. The clear winner is the cat flea that now <a href="http://dx.doi.org/10.1016/j.vetpar.2011.03.035">dominates Australian cities</a> and is the primary culprit behind the itch which commonly afflicts cats and dogs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/112453/original/image-20160223-25876-sit6e6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/112453/original/image-20160223-25876-sit6e6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/112453/original/image-20160223-25876-sit6e6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=378&fit=crop&dpr=1 600w, https://images.theconversation.com/files/112453/original/image-20160223-25876-sit6e6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=378&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/112453/original/image-20160223-25876-sit6e6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=378&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/112453/original/image-20160223-25876-sit6e6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=475&fit=crop&dpr=1 754w, https://images.theconversation.com/files/112453/original/image-20160223-25876-sit6e6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=475&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/112453/original/image-20160223-25876-sit6e6.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>
<figcaption>
<span class="caption">Dog on the left and cat flea on the right.</span>
<span class="attribution"><span class="source">Jan Slapeta</span></span>
</figcaption>
</figure>
<p>The cat flea is so successful because the cities, houses and in fact Australian climate is just perfect for this parasite. The cat flea could not ask for more. </p>
<p>The cat flea adults are blood-sucking, so they stay on the dog or a cat (or even us!). Their immature eggs drop on the ground where they develop into larvae. These larvae need sandy soil, 80% humidity and 25°C warmth – pretty close to what we enjoy on a daily basis in many parts of coastal Australia.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/112455/original/image-20160223-25888-u7f59w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/112455/original/image-20160223-25888-u7f59w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/112455/original/image-20160223-25888-u7f59w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/112455/original/image-20160223-25888-u7f59w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/112455/original/image-20160223-25888-u7f59w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/112455/original/image-20160223-25888-u7f59w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=467&fit=crop&dpr=1 754w, https://images.theconversation.com/files/112455/original/image-20160223-25888-u7f59w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=467&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/112455/original/image-20160223-25888-u7f59w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=467&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cat flea larvae measure around 4 mm and may be crawling all over your sofa!</span>
<span class="attribution"><span class="source">Jan Slapeta</span></span>
</figcaption>
</figure>
<p>Fleas evolved through the millennia to drink blood and produce large number of eggs. Each adult female can produce around 40 eggs a day. That is a lot of eggs if your pet has just 20 adults and half are females. It adds up to 400 a day and 12,000 in a month! What’s more, 20 fleas is not that many for an Australian dog; some dogs or cats harbour hundreds of fleas. </p>
<p>Fleas are bloodthirsty creatures, but their digestive tract cannot use all the blood and so much of it comes out as dried faeces (“flea dirt”). </p>
<p>This dried blood drops into the animal fur and further drops wherever the animal spends most time. Maybe your sofa, maybe your carpet. That is exactly where eggs drop as well. The larvae that hatch from the eggs are surrounded by pieces of dried blood - their daily meal. The adult fleas thus feed not only themselves, but also their offspring. </p>
<p>It is nice to live with humans. We provide the perfect niche not just for our pets but also their fleas.</p>
<p>But back to our <em>T. rex</em>. Interestingly, the most recent analyses show that <a href="http://dx.doi.org/10.1016/j.ympev.2015.04.027">fleas first evolved to feed on marsupials</a>. Fleas were likely an obscure group during the dinosaur age. </p>
<p>Fleas came to prominence after the dinosaur extinction event, likely because of new emerging niches on fury mammals which survived the likely asteroid collision which caused a dust cloud and cooled the earth.</p>
<h2>Elite athletes</h2>
<p>The high jump is a flea’s favourite event. The larvae that feed on the dried blood subsequently form a cocoon with a new adult inside. The new flea won’t hatch immediately. It will wait and wait (for several months). </p>
<p>If you’ve seen the film <a href="http://www.imdb.com/title/tt0090605/">Aliens</a>, you may recall the scene in which the alien “eggs” are activated by the presence of the human heroes. That is exactly what fleas in their cocoons are waiting for as well. Dogs or even you walk around and flea emerges and unleashes its legs springing power to land on a new host. </p>
<p><em>Fleas can jump up to 25 cm high!</em></p>
<p>In heavily infested households, human victims have flea bites on their legs up to 25 cm from the ground - a telltale sign of infestation. Such a jump would mean that a human athlete would be jumping as high as 305 m over the Sydney Tower. The acceleration is comparable to a Space Shuttle launch. </p>
<h2>Living better with fleas</h2>
<p>In coastal Australia, the flea battle is on year-round. Will we ever be able to eliminate them all together? Unlikely! </p>
<p>Fleas are here to stay. Reducing their numbers is well-justified, not just because of the itchiness they cause to our pets. Fleas can carry some of their own little fleas or human diseases with them. Diseases such as Cat Flea Typhus (<em>Rickettsia felis</em>) and Cat Scratch Fever (<em>Bartonella henselae</em>) are transmitted by fleas. </p>
<p>Year round control with parasiticides (there are lots of good ones to choose from) with bit of environmental control (vacuuming) is the way to go. Don’t despair, talk to your vet. They are the experts in flea management.</p>
<p><em>This article is part of a <a href="https://theconversation.com/au/topics/hidden-housemates">series profiling our “hidden housemates”</a>. Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a></em>.</p><img src="https://counter.theconversation.com/content/54900/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jan Slapeta teaches veterinary parasitology at the University of Sydney.</span></em></p>Fleas have lived with people for as long as people have lived with pets.Jan Slapeta, Associate Professor in Veterinary Parasitology, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/547432016-02-16T18:24:02Z2016-02-16T18:24:02ZHidden housemates: meet the moulds growing in your home<figure><img src="https://images.theconversation.com/files/111575/original/image-20160215-8211-15wm44y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Your home is full of fungi. </span> <span class="attribution"><span class="source">Mould image from www.shutterstock.com</span></span></figcaption></figure><p><em>Home alone? Hardly. Our homes are positively swarming with creatures of all kinds. In our new series, we’ll be profiling the “hidden housemates” that live with us.</em> </p>
<p>Our offices and homes are full of airborne spores from fungi, and for the most part we never even notice them.</p>
<p>Whether you like to think about it or not, you’re covered in microorganisms. Absolutely teeming with them from head to toe. Your body is covered and filled with bacteria called commensals, which inhabit the microscopic valleys of your skin and recesses of your gut. These organisms for the most part never cause you any harm, and in fact protect you from being colonised by disease-causing organisms. </p>
<p>In the same way that you’re a walking zoo of microbes, the world around you is peppered with invisible microorganisms. </p>
<h2>Ancient relationship</h2>
<p>This isn’t a new relationship though. Humans have been cohabiting with fungi for a very long time. </p>
<p>Ancient Egyptian bakers and brewers were harnessing natural yeasts more than <a href="http://search.proquest.com/docview/213552171?pq-origsite=gscholar">4,000 years ago</a>, but it was only in the 1850s that we realised it was microbes that were responsible for <a href="http://onlinelibrary.wiley.com/doi/10.1002/1097-0061(20000615)16:8%3C755::AID-YEA587%3E3.0.CO;2-4/full">leavening bread and making alcohol</a>.</p>
<p>We’ve also known for a very long time that unpreserved foods spoil, growing conspicuously fuzzy tufts of blue and green mould. The kinds of moulds that make our bread and make forgotten oranges go fluffy are really the weeds of the fungal world.</p>
<p><em>Penicillium</em> (this is the same fungus involved in the discovery of the first antibiotics, but that’s another story) and <em>Aspergillus</em> are the microscopic equivalent of soursobs and dandelions, and look fairly similar in a lot of ways. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/111592/original/image-20160216-6548-1fbxe2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/111592/original/image-20160216-6548-1fbxe2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111592/original/image-20160216-6548-1fbxe2z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111592/original/image-20160216-6548-1fbxe2z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111592/original/image-20160216-6548-1fbxe2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111592/original/image-20160216-6548-1fbxe2z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111592/original/image-20160216-6548-1fbxe2z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Aspergillus niger, the fungal dandelion.</span>
<span class="attribution"><span class="source">Michael Taylor</span></span>
</figcaption>
</figure>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/111613/original/image-20160216-8211-e8jows.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/111613/original/image-20160216-8211-e8jows.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111613/original/image-20160216-8211-e8jows.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111613/original/image-20160216-8211-e8jows.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111613/original/image-20160216-8211-e8jows.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111613/original/image-20160216-8211-e8jows.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111613/original/image-20160216-8211-e8jows.png?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">Penicillium, the source of the antibiotic penicillin.</span>
<span class="attribution"><span class="source">Michael Taylor</span></span>
</figcaption>
</figure>
<p>Walk through any park, or into any building the world over and you’ll probably be picking up spores from <em>Penicillium</em> and <em>Aspergillus</em>; up to a <a href="http://ibe.sagepub.com/content/23/7/1002.short">several hundred per cubic metre of air is normal</a>. In fact when you’re looking at indoor fungi, if you don’t find these two floating around you often question if you’ve taken your samples correctly.</p>
<h2>Is your house ‘killing you’?</h2>
<p>Indoor airborne fungi have become implicated in “<a href="https://en.wikipedia.org/wiki/Sick_building_syndrome">sick building syndrome</a>” and claims that our homes are “<a href="https://www.youtube.com/watch?v=2q6OqA7_Etc">killing us</a>”. </p>
<p>There is some sense mixed in with the scare here. These kinds of organisms can colonise our houses and <a href="https://theconversation.com/health-check-how-does-household-mould-affect-your-health-48341">cause serious illness</a> but it’s unlikely that you’re in imminent danger. </p>
<p>Mould becomes a problem when there is moisture, or the inability for it to escape. After large rainfall or flood events, porous materials in buildings like wood, insulation, carpet and furnishings absorb a lot of water. </p>
<p>This water can then support the growth of fungi and fill cavities and hidden areas with very humid and stagnant air – perfect conditions for problem moulds such as <em>Stachybotrys</em>, the <a href="http://toxsci.oxfordjournals.org/content/104/1/4.long">toxic black mould</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/111612/original/image-20160216-8211-1j2jqed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/111612/original/image-20160216-8211-1j2jqed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111612/original/image-20160216-8211-1j2jqed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111612/original/image-20160216-8211-1j2jqed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111612/original/image-20160216-8211-1j2jqed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111612/original/image-20160216-8211-1j2jqed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111612/original/image-20160216-8211-1j2jqed.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">Stachybotrys, or Black mould.</span>
<span class="attribution"><span class="source">Unknown</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/111617/original/image-20160216-22545-1t6zr4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/111617/original/image-20160216-22545-1t6zr4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/111617/original/image-20160216-22545-1t6zr4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/111617/original/image-20160216-22545-1t6zr4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/111617/original/image-20160216-22545-1t6zr4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/111617/original/image-20160216-22545-1t6zr4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/111617/original/image-20160216-22545-1t6zr4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/111617/original/image-20160216-22545-1t6zr4u.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">If your bathroom is looking like this, you may have a problem…</span>
<span class="attribution"><span class="source">Black mould image from www.shutterstock.com</span></span>
</figcaption>
</figure>
<p>Most of the time though the fungi that turn up after water damage shouldn’t poison you or cause infection, but will probably smell musty and cause allergy-like symptoms until the problem is fixed. </p>
<p>In many cases fixing the root cause may be relatively simple, with the first step always being to ensure that whatever caused the water to accumulate is fixed and any excess moisture is dried out. Non-porous surfaces are often simply able to be wiped clean of all visible mould with a detergent or cleaning spray. </p>
<p>Soft furnishings, clothes and carpets should be thoroughly vacuumed and washed if possible, or thrown out if extensively contaminated. Porous surfaces are increasingly more difficult as wiping the surface clean may not actually remove the mould and will likely need to be replaced to fully solve the problem. Extensively damaged homes after a flood may be beyond remediation, and any clean-up operations on this scale should always involve a professional.</p>
<p>But it’s not just leaky roofs that encourage fungi to come indoors though, our push towards ultra-efficient green buildings can <a href="http://link.springer.com/article/10.1023/A:1015592224368">cause similar problems</a>. </p>
<p>To reduce energy costs, we often design our air-conditioning systems to recycle as much of the indoor air as possible, which over the course of the day can slowly push up carbon dioxide and moisture in the air. </p>
<p>If this isn’t removed, it can leave you feeling sleepy and the air feeling heavy whilst providing an opportunity for fungi to take over.</p>
<h2>The fungal garden in your home</h2>
<p>We’re often told to aim for a lifestyle with “balance”. The same is true for our microscopic housemates. </p>
<p>If you end up with one single species dominating <a href="http://www.who.int/indoorair/publications/7989289041683/en/">you may have a problem</a>. On the other hand a mixture of species shows that everything is relatively in order and is an indicator of a healthy environment.</p>
<p>The mixture of airborne fungi does change from place to place, but not as dramatically as you’d expect. The same specimens tend to turn up the world over: <em>Penicillium</em>, <em>Aspergillus</em> and <em>Cladosporium</em>, alongside a handful of other common fungi. </p>
<p>If you live near agricultural pastures, you may find a greater abundance of plant pathogens like <em>Alternaria</em>, <em>Stemphylium</em> and <em>Fusarium</em>. The species may change if you’re in different regions of the world, but overall your lungs probably contain similar spores to your relatives in Spain or Japan. </p>
<p>If you live in California’s San Joaquin Valley, however, you are in the unlucky position of being tens of thousands of times more likely to be exposed to infectious spores from the fungi <a href="http://jcm.asm.org/content/45/1/26.short"><em>Coccidioides immitis</em></a>, which cause the otherwise relatively rare condition of fungal pneumonia. </p>
<p>But if it makes you uncomfortable to think about the invisible world pulsing with life around you, relax. Generally a healthy mixture of fungi can indicate a healthy home, and I promise you that life is better with fungi in it than without. </p>
<p><em>Are you a researcher with an idea for a “hidden housemates” story? <a href="mailto:james.whitmore@theconversation.edu.au">Get in touch</a></em>.</p><img src="https://counter.theconversation.com/content/54743/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Taylor 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>Moulds and fungi have been living with us for thousands of years - you just might not think about them until they become a problem.Michael Taylor, Lecturer, School of the Environment, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.