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Madagascan Hissing Cockroach
(Gromphadorhina portentosa).
This insect is 8 cm (3 in) long.

Scientific classification


A cockroach is an insect of the order Blattodea (or Blattaria). The name of the order is derived from Greek blatta, meaning cockroach. The American Cockroach (Periplaneta americana) is about 3 cm long. The German cockroach (Blattella germanica) is about 1.5 cm long. Tropical cockroaches are much bigger. When infesting buildings, cockroaches are considered pests.



Cockroaches are either scavengers or omnivores. They are most common in tropical and subtropical climates. Some species are in close association with human dwellings and widely found around garbage or in the kitchen.

Female cockroaches, or henroaches, are sometimes seen carrying egg cases on the end of their abdomen; the egg case of the German Cockroach holds about 30-40 long, thin eggs, packed like frankfurters in the case called an ootheca.

The eggs hatch from the combined pressure of the hatchlings gulping air and are initially bright white nymphs that continue inflating themselves with air and harden and darken within about four hours. Their transient white stage while hatching and later while molting has led to many individuals claiming to have seen albino cockroaches.

A female German cockroach carries an egg capsule containing around 40 eggs. She drops the capsule prior to hatching. Development from eggs to adults takes 3-4 months. Cockroaches live up to a year. The female may produce up to eight egg cases in lifetime. In other words, in favorable condition it can produce 300-400 offspring.

A regular cockroach, however, can produce an extremely high number of eggs in her lifetime. She lays up to 100 eggs in each egg sac. She only needs to be inpregnated once to be able to lay eggs for the rest of her life, allowing one single cockroach to lay over a million eggs in her lifetime.

The world's largest cockroach is the Australian giant burrowing cockroach, which can grow to 9 cm in length and weigh more than 30 grams. Comparable in size is the giant cockroach Blaberus giganteus, which grows to a similar length but is not as massive. Flying winged roaches are native to Palm Springs, California.

Cockroaches are mainly nocturnal, and will run away when exposed to light. Roaches are actually very clean insects, even though they eat garbage. They are called the custodians of nature. They only live in houses where there are crumbs to eat or the garbage can is uncovered. They lay eggs inside the house's hollow walls. Is it commonly said that for every one roach seen, there are at least a hundred more hidden (necessarily, though, this claim is apocryphal). The roach is also one of the hardiest insects on the planet living for a month without food and remaining alive headless for upto a week. It can also hold its breath for 45 minutes and has the ability to slow down its heart rate. Infact this is the only insect that can surive a nuclear blast as it is much more tolerant to nuclear radiation.

Closeup of a cockroach
Closeup of a cockroach

Select species

Madagascar Hissing Cockroach

The Madagascar hissing cockroach (Gromphadorhina portentosa) is a large flightless insect from the forests of Madagascar. It lives under the bark of trees or in leaf litter, feeding on plant matter including leaves and fallen fruit. It is a Ovoviviparous organism.

Any predator that catches one of these cockroaches is in for a double shock. The legs of this insect are covered in needle-sharp spines and the cockroach can make a loud hissing sound. It does this by forcing air out of the breathing holes that run along the side of its body.

This is one of the largest cockroaches in the world and can reach 8 cm (3 inches).

Although they live in the forest, they are attracted by house lights, and will sometimes creep through open windows. However, they are harmless and will soon leave when disturbed.

The Madagascan Hissing Cockroach is often used in television programmes and films where a large scary-looking insect is required.


The largest known cockroach by wingspan is a Megaloblatta longipennis, with a 18-cm wingspan. The largest by weight is a 50-g Macropanesthia rhinocerus. The smallest species is Attaphila fungicola, reaching only 4 mm.

External link

  • cockroach pictures ( shares pictures and facts on cockroaches and their behavior, feeding habits and life cycle.

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