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Gromphadorhina porentosa
Habitat: primarily found in the tropical lowland rainforests of Madagascar. They tend to live in the dry litter on the forest floor.
Physical Description: 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, from mahogany brown to black, and 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 bumps or tubercles behind their head, these structures are much smaller in females. These horns are known as pronatal humps. Gromphadorhina portentosa is one of the largest species of the cockroaches in the world, adults are 5.1 to 10.2 cm long, with males growing larger than females.
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 and do not fight with one another or with males. The cockroaches are nocturnal and they avoid light.
Diet: Madagascar hissing cockroaches are detritivores. Their most frequent food is decaying plant material, including fallen fruit, because it is so readily available. They also eat smaller insects and animal carcasses.
Reproduction: Male Madagascar hissing cockroaches produces 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.
Status: Because the Madagascar hissing cockroach is only found in Madagascar, little conservation efforts have been done.
Fun Facts:
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This species is part of the nutrient cycling process in Malagasy forests. These forests are important as sources of timber, for water quality, and sources of other natural products. |
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The mite is a common parasite of this cockroach. These mites form small clumps of four to six individuals at the base of the leg of their cockroach host. While it was originally thought that this mite was sanguinivorous (blood-sucking), recent studies showed that the mite simply "shares" in a cockroach's food items. |
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Hissing cockroaches probably have many types of predators, but there are few documented relationships. Arachnids, ants, tenrecs, and some ground-feeding birds are likely predators. As previously mentioned, an anti-predatory strategy is an alarm hiss - producing a loud snake-like noise that may startle potential predators. |
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