Madagascar hissing cockroaches are large cockroaches, usually about 2 to 3 inches long and 1 inch wide. They are named after the island of Madagascar, off the coast of Africa. Other common names for this insect include Madagascar cockroach, giant cockroach, hissing cockroach or just hissers. Their scientific name is Gromphadorhina portentosa.
Madagascar hissing cockroaches are endemic species, only found on the island of Madagascar. They are nocturnal creatures that mostly avoid the light and live in tropical lowland forests and rainforests, primarily on the forest floor. They are decomposers, helping to cultivate organic material back into soil. They feed on fallen fruit, vegetation and may also feed on other smaller arthropods. They are a food source for many animals including ground-feeding birds, tenrecs (a mammal similar to shrews and hedgehogs, but found only in Madagascar) and arachnids.
The nearest relatives of the Madagascar hissing cockroach include mantids, grasshoppers, stick insects and termites. Madagascar cockroaches are known as “living fossils,” as these insects are very similar to the prehistoric cockroaches that lived on Earth long before the dinosaurs. Unlike most cockroaches, they are wingless. They are excellent climbers and can scale smooth surfaces such as glass. Males can be distinguished from females by their thicker, hairier antennae and the pronounced "horns" on the pronotum (a section of the body just behind the head).
Madagascar hissing cockroaches produce a hissing sound for which they are famous. Four types of hisses with different social purposes and amplitude patterns have been identified: a male combat hiss, two types of courting and mating hisses and an alarm hiss (a loud snake-like hissing that startles predators). The cockroach hisses by pushing air forcefully through a pair of modified spiracles, which are small openings through which air is taken into the respiratory system of the insect. Spiracles are arranged along the sides of the thorax and abdomen. They are thought to be one of the only insects that use their spiracles to make sound. Most other insects produce sound by rubbing parts of their body together or by vibrating diaphragms.
Male Madagascar cockroaches do much of the hissing as they establish territories and defend themselves from other adult males. Territory sizes are small. A male may sit on a rock for months and defend it from other males, leaving only to find food and water. Aggressive hissing and posturing behavior is used to warn other males and predators away - the male that is larger and hisses more usually wins. The dominant male will stand on its "toes," which is called stilting. Stilting is a way for males to "show off." As a defense mechanism, the males will use the humps on their pronotum. A pronotum is a plate-like structure that covers most of their thorax. Fighting between males does not appear to cause injury.
Females and nymphs are more social and do not fight with one another or with males. Because of this, females are less likely to hiss, although on rare occasions the whole colony will hiss in unison. The reason for this behavior is not yet understood. Females carry the ootheca (egg case) internally, and release young nymphs only after the eggs have hatched. As in some other wood-inhabiting roaches, the parents and offspring will commonly remain in close physical contact for extended periods of time. In captivity, these insects can live two to five years.
Madagascar hissing cockroaches are docile, easy to maintain and often kept as pets. They require a small living area with a place for them to hide, because they prefer to stay out of the light. Due to their propensity to climb, the living area must be tested to see if they can climb out of the enclosure. Fish tanks or terrariums found in pet stores work well, but it is wise to coat the top few inches of glass with petroleum jelly to keep them from getting out of the habitat. They can live on fresh vegetables along with any kind of pellet food that is high in protein, such as dry dog food. Water can be provided by keeping a wet sponge in the habitat.
In the United States, some states require permits before this species can be kept as a pet or in breeding colonies. This is to prevent accidental introduction of this species into environments where they can survive. They currently do not infest structures in the U.S.
In some places, people eat hissing cockroaches because they are high in protein and readily accessible. The eating of insects is called “entomophagy.” Madagascar hissing cockroaches have been featured in many popular films and television shows. Challenges to eat live Madagascar cockroaches have also been popular on reality shows and in contests.