Bed bug mating behavior is something else. The male does not inseminate the female’s genital opening directly, as with other insects. His genital organ is transformed into a kind of hypodermic needle that can pierce the female’s exoskeleton and ejaculates the sperm directly into her abdomen. It is quite a violent process that looks more like a murder attempt than mating, and in technical terms it is called traumatic insemination. The injected sperm travel via the blood. In these insects it does not run in the veins, but washes freely around the organs. The sperm end up in a couple of pouches on the female’s oviducts, called spermathecae. Here they remain viable as long as the body temperature is normal and there are plenty to fertilize all the eggs the female lays in its lifetime.

There is nothing to suggest that the two sexes can recognize each other from appearance, special pheromones or behavior. A male in rut will attempt to mate with other bugs of a certain size and that has just sucked blood. This means that it will also attempt to mate with other males. However, a complete mating with other males is in almost all cases prevented. This is done by a particular fragrance, an alarm pheromone, being released by the harassed male. Like many other insects, bed bugs can communicate by using specific pheromones. The pheromones are released from special scent glands in specific situations, and can trigger a specific behavior in similar species. Among other things, bed bugs can make use of an alarm pheromone when they are in danger. It deters the bed bugs that are nearby, causing them to spread out so they do not all become an easy prey for a predator. This pheromone is quite volatile, and soon the bed bugs get back together.

It has been found that a male bed bug in danger of rape emits this deterrent alarm pheromone. In most cases, it will cause the male in rut to refrain from completing the process.

If the opportunity presents itself, the common bed bug will mate with the bat bug (Cimex hemipterus), but the eggs are usually sterile.