Madagascar hissing cockroach
What is the Madagascar hissing cockroach known for?
Where is the Madagascar hissing cockroach endemic to?
How do Madagascar hissing cockroaches reproduce?
Madagascar hissing cockroach, (Gromphadorhina portentosa), large species of cockroach known for its ability to make hissing sounds. The insect is one of the largest of all cockroach species (the largest being the South American Megaloblatta longipennis) and is endemic to Madagascar. Like most other cockroach species, the Madagascar hissing cockroach is not a pest and does not infest human dwellings. The insect is docile when handled by humans and is sometimes kept as a pet.
Physical description
The Madagascar hissing cockroach is 5–7.5 cm (2–3 inches) long, and it can weigh up to 22.7 grams (0.8 ounce), about the weight of an alkaline AA battery. It has a flat oval body, and its shiny exoskeleton is hard, thick, and waxy. The insect’s head and pronotum (the part of the thorax behind the head) are dark brown to black, and its abdomen is brown. The cockroach has one pair of long antennae. On the pronotum are protrusions called pronotal humps. These are relatively large and hornlike on males and very small or nonexistent on females. The Madagascar hissing cockroach can move quickly on its six legs, and, unlike many other cockroach species, it does not have wings. It can climb most surfaces, even smooth glass, because of padlike and hooklike structures on its feet.
Like other insects, the Madagascar hissing cockroach does not have lungs and thus does not hiss through its mouth. Instead, like other insects, it takes in oxygen and expels carbon dioxide through holes, called spiracles, in the sides of its thorax and abdomen. The spiracles are located at the ends of tracheae, or tubules, that carry oxygen throughout the body. The Madagascar hissing cockroach makes its characteristic hissing sound by forcing air from a pair of modified abdominal spiracles. This ability is unusual for invertebrates, which usually make sound by rubbing body parts together or by vibrating membranes.
Natural history
The Madagascar hissing cockroach lives in a large semi-social colony on the floor of a tropical forest, where it hides under fallen leaves and logs during the day. At night it emerges to scavenge for food. The insect is an opportunistic omnivore and a detritivore, feeding on dead and decomposing organic matter, such as fallen fruit, decaying plant and animal matter, and decomposing wood. It plays several important roles in the ecosystem by recycling nutrients and returning them to the soil as well as by providing a food source for lemurs, birds, lizards, and other animals.
The Madagascar hissing cockroach is ovoviviparous, meaning that the female produces eggs that develop and hatch within the maternal body. After mating with a male, the female produces an ootheca, or egg case, inside her abdomen to incubate as many as 60 fertilized eggs. Approximately 60 days later the eggs hatch inside her body, and she then pushes out the nymphs to live independently. The nymphs molt several times before becoming sexually mature adults; adults do not molt. Madagascar hissing cockroaches have a lifespan of two to five years in the wild and usually not longer than five years in captivity.
Male Madagascar hissing cockroaches battle each other to acquire mates and defend territory. During the fights, they hiss and push each other with their horns and abdomens. In addition, they stand on their “toes,” an action called stilting, to intimidate each other. The cockroaches are not hurt during these battles. The male that is larger and hisses more usually wins. Males hiss in response to danger and in order to scare a predator, which may give them a chance to get away. Adult females and older nymphs also can hiss, but they do so only when they detect danger. Females do not fight with each other or with males.
