And speaking of painful penis....
Of all the disturbing things about bedbugs, their mating habits may be the worst. Cimex lectularius have evolved a breeding technique called "traumatic insemination," and it's even more horrible than it sounds.
A male bedbug's penis is literally a weapon—a sharp, brown hypodermic hook that forgot about the female reproductive canal long ago. Here's how he uses it: The male pounces on the female, holds her firmly while she struggles, and gouges his hook through her exoskeleton, squirting his sperm directly into her body cavity. The sperm swims through her hemolymph (a bug's version of blood) and, if the mating wound doesn't develop a serious infection and kill her, eventually swims to her ovaries.
Biologists used to believe males and females of a given species evolved together for sexual fitness, the Darwinian version of romance. But bedbugs, scientists have found, have engaged in a millennia-long struggle of "sexually antagonistic coevolution" in which individual males damage individual females for overall reproductive advantage. Female bedbugs have counterevolved "spermalege," a special sperm-receptacle organ in the abdomen that helps absorb the trauma—if the hypodermic penis hits it. Bedbugs aren't exactly careful maters. Male bugs sometimes traumatically inseminate each other, though scientists aren't sure whether this is a function of sexual competition or just carelessness. Regardless, sex is bad for female bedbugs. A 2003 study for the Royal Society of London found that the more sex a female bedbug has, the shorter her life will be.
A bed infested with bedbugs isn't just a party for bloodsuckers that will make you itch—it's also a Verdun of buggy sexual warfare.