Madagascar Hissing Cockroach

Almost all insects that make noise do it by stridulation — rubbing one hard body part against another, the way a cricket rubs its wings or a grasshopper rubs a leg against a wing. The Madagascar hissing cockroach is one of very few insects that instead makes sound the way a mammal does, by moving air. It has a pair of unusually large spiracles (the holes insects breathe through) on the fourth abdominal segment, and by sharply contracting its abdominal muscles it forces air out through these narrowed openings, producing an audible hiss lasting a second or two. Because the mechanism is respiratory rather than mechanical, the sound can be produced by nymphs and adults of both sexes, even though only adults have the full repertoire.

For different reasons depending on the situation. The best-known is the disturbance or alarm hiss — when a cockroach is grabbed, pinned, or attacked it gives a loud, startling hiss that is widely thought to imitate a striking snake and make a predator such as a lemur, bird, or tenrec hesitate or drop it. Adult males also use two social hisses that females and juveniles do not — a fighting hiss during contests with other males, where the louder, more persistent hisser usually wins and rarely has to escalate to physical combat, and a softer courtship hiss directed at females. A dominant male hisses more, holds territory, and mates more.

Yes. Adult males have two rounded projections on the pronotum, the shield over the thorax, that look like blunt horns, and they use them in shoving matches. Two rival males face off, hiss at each other, then push front-to-front, each trying to get his horns under the other and flip or drive him back, sometimes rearing up on their hind legs. The loser retreats. Males with larger horns and bodies win more often and control the best positions on a log or rock, where they intercept and court passing females. Females and immature males lack the horns and do not fight this way, so the structure is a clear product of sexual selection.

They are one of the most popular pet and educational insects because they are large, slow, docile, cannot fly, cannot climb smooth vertical surfaces like glass, do not bite, and live for years. A colony needs only a ventilated tank with a secure lid, a warm spot, some bark or egg-carton hides, a shallow water source or moist substrate, and fresh vegetables and fruit plus a dry protein source. They breed readily. The main cautions are legal and practical — some places (parts of the US, for example) restrict keeping them because an escaped tropical population could become a pest, so a lid and responsible disposal matter, and a few keepers develop an allergy to insect dust over time.