Central american giant cave cockroach, Brazilian cockroach
Blaberus giganteus, the Central American giant cave cockroach or Brazilian cockroach, is a cockroach belonging to the family Blaberidae. One of the world's largest cockroaches, it is native to the warm parts of the Neotropical realm.
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NocturnalNocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal",...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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starts withBlaberus giganteus is considered one of the largest cockroaches in the world, with males reaching lengths of up to 7.5 cm (3.0 in) and females 10 cm (3.9 in), although others list 9 cm (3.5 in) as the maximum length. These cockroaches are lightly built with flattened bodies, allowing them to hide in cracks from predators. Their bodies are brown with black markings. The wingspan of these insects is usually around 15 cm (6 in). Both males and females bear paired appendages (cerci) on the last abdominal segment, but only the males have a pair of tiny hair-like appendages called styli. Adults bear two pairs of wings folding back over the abdomen. The heavier females are less likely to fly.
This species is endemic to the Neotropics and can be found in caves and rainforests in Mexico, Guatemala, Panama, Colombia, Ecuador, Venezuela, Costa Rica, Brazil, Trinidad and Tobago, Cuba, Hispaniola (Dominican Republic), Guyana, Suriname, and French Guiana. Habitat preferences include areas of high moisture and little light, such as caves, tree hollows, and cracks in rocks.
As typical for all roaches, individuals undergo hemimetabolous metamorphosis, which means the change from juvenile to adult is gradual. The three distinct stages in their lifecycle are egg, nymph, and adult. Only adults are able to reproduce and have wings. Prolonged nymphal stages, along with additional molts, can sometimes occur in B. giganteus for a number of reasons. One hypothesis is that the absence of the jostling and mutual stimulation which are found often in colony life could slow the developmental process. In other instances, lower temperatures and reduced humidity can lead to delayed maturation and an increase in the number of molts. This is a response by the insect to unfavourable habitat conditions and can also be seen as a predatory response. Their lifespans can last up to 20 months depending on habitat conditions and diet.
Cockroaches always have three legs in synchronous contact with the ground during movement. The three legs are classified as the leading leg, middle leg, and trailing leg and the leading and trailing leg from one side with the middle leg of the other side forms a tripod. The leading leg pulls the body, while the trailing leg pushes the middle leg forward. The middle leg is important because it acts as a pivot and creates the characteristic zigzag locomotion. The process is repeated with the next tripod, and to move forward, the tripods alternate. The ability of cockroaches to have ground reaction force distributed equally to these three legs is explained by joint torque minimization, which has been shown to help limit mechanical, energetic, and metabolic demands, and can also decrease the axial load on a single leg. Cockroaches can easily walk up a 45° slope on a smooth surface with little to no difficulty. However, aged cockroaches or cockroaches with damaged tarsi can overcome such slopes only with difficulty.
Blaberus giganteus is a nocturnal omnivore and a scavenger, but the majority of its diet is decaying plant material. Other food choices include bat guano, fruit, seeds, and carrion. It is often associated with bats roosts, both in caves and hollow dung. They also prefer sweets, meats, and starches as their daily meal.
Two chemical signals play important roles in the sexual behaviour of B. giganteus. The sex pheromone is released by the female and used in attracting mates that are long distances away. The male produces an aphrodisiac sex hormone from his tergal glands that encourages female mounting. Females choose the males with which they will mate, so this sexual selection becomes a major pressure and driving force behind natural selection. Carbohydrate intake has been found to be related to male sex pheromone expression, dominance status, and attractiveness more so than protein. Males have been shown to have a preference for a high-carbohydrate diet versus one focused on protein. This would suggest they are actively increasing their carbohydrate consumption to maximize their reproductive fitness and attractiveness to potential female mates. After mating, the female B. giganteus is pregnant for life and stores the fertilized eggs in her ootheca, where they are incubated for roughly 60 days. When the eggs are about to hatch, the female expels the ootheca so the nymphs can break free and feed on their first meal, which consists of the ootheca. After eating their fill, the young nymphs burrow into soil or somewhere dark and remain there until they have molted numerous times and reached maturity.
