Madagascar Hissing Cockroach

Characteristics

Like most insects, Gromphadorhina portentosa has a head, thorax, abdomen, and 6 legs. Unlike many cockroach species, they do not possess wings. Their exoskeleton is dark, ranging from mahogany brown to black. It is very thick, hard, and waxy. They have pads and hooks on their feet that allow them to climb smooth surfaces. Males possess a pair of large pronatal horns behind their head, these structures are much smaller in females. Gromphadorhina portentosa is one of the largest species of cockroaches in the world. Adults are 2-4 inches, with males growing larger than females.

Species Specifics

Cockroaches belong in the class of arthropods Insecta, and are classified into the order Blattaria. Five families of cockroaches are in this order: Cryptocercidae, Blattidae, Polyphagidae, Blattellidae and Blaberidae. The Madagascar hissing cockroach is in the family Blattidae. Cockroaches are found on every continent, including Antarctica.

Physical Characteristics

The Madagascar hissing cockroach has a unique defense mechanism. Along each side of its body is a row of holes, called spiracles. These spiracles are used for respiration. When the Madagascar hissing cockroach is threatened, it depresses its abdomen, ejecting air out of its spiracles. This produces a loud hissing noise which can startle a predator, giving the cockroach a chance to escape.

Ecology

Habitat

Forages on the floor of tropical forests, near river banks and around logs or trees.

Distribution

As its name suggests, the Madagascar hissing cockroach is found only on the island of Madagascar.

Diet

The majority of their diet consists of various decaying plant matter. Occasionally they will also feed on animal matter.

Ecological Web

For humans, cockroaches pose little threat. Practically all species of cockroaches are beneficial to their environment. They are an invaluable aid in recycling a large majority of the Earth's dead or decaying plant and animal matter. For example, tropical forests have been called "green deserts," because their soils are poor in nutrients. The forest vegetation appears to be lush, but it has survived only through ingenious life-support systems. Cockroaches are one of the building blocks of these systems. Without cockroaches, dead and decaying vegetation would smother tropical forests.

Activity and Behavior

Activity Pattern

Sheltered during the day, this cockroach is most active at night for foraging.

Behavior

Hissing is also used as a means of communication during courtship and mating, or by males to defend their territories from other males.

Social Behavior

Male Madagascar hissing cockroaches establish territories that are defended from other adult males. Aggressive hissing and posturing behavior is used to warn intruders away. The male that is larger and hisses more usually wins. The dominant males stand on their "toes," which is called stilting. Stilting is a way for males to "show off." The males use their pronatal humps when fighting other males to defend territories. Fighting between males does not appear to injure the males. Females and nymphs are more social. They do not fight with one another or with males.

Reproductive Behavior

Male Madagascar hissing cockroaches produce acoustic sounds or hissing during courtship interactions with females. Males typically produce two types of signals, a calling sound and a courtship sound. The calling sound is a long distance song that is used to attract females while the courtship sound is used more during close range interaction. Adult male hissing cockroaches defend mating territories from other males, and attempt to monopolize mating with all the females in their territory. Males interact by hissing, and in bouts of pushing and shoving. Cockroach mating can occur year around, but only when the climate is warm.

Offspring

Up to 60 in an ootheca.

Conservation

Status

Not Evaluated

Historical

Current Threats

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