It is fair to say we belong to a species obsessed by sex. We are among the only species to have sex for fun, not just for reproduction. For some other species, though, sex is far from fun. In fact, as two recent review papers show, it is a war zone, involving penis fencing and love darts.
In 1897, the Italian zoologist Constantino Ribaga discovered a strange organ in female bedbugs, halfway up the abdomen. He suggested they used it to produce sound, like cicadas. But something wasn’t right: in the bundle of cells underneath this organ he found large quantities of sperm.