cockroaches

Cockroaches are insects of the Order Blattodea. The name of the order is derived from Greek for "cockroach," blatta. There are roughly 3,500 species in 6 families. Cockroaches exist worldwide, with the exception of the polar regions. Cockroaches are also simply known as "roaches".

The English word cockroach is derived from the Spanish cucaracha, meaning "chafer, beetle".

Among the most well-known species are the American cockroach, Periplaneta americana, which is about 3 cm long, and the German cockroach, Blattella germanica, about 1½ cm long, and the Asian cockroach, Blattella asahinai, also about 1½ cm in length. Tropical cockroaches are often much bigger, and extinct cockroach relatives such as the Carboniferous Archimylacris and the Permian Apthoroblattina were several times as large as these. When infesting buildings, cockroaches are considered pests; out of the thousands of species, however, only a handful fall into this designation.

Contents [hide]
1 Evolutionary history and relationships
2 Biology
3 Selected species
4 Behavior
5 Cockroaches and health risks
6 Habitat
7 Interesting facts
8 Pest control
9 Popular culture
10 History
11 Miscellaneous
12 External links
13 References



[edit] Evolutionary history and relationships
The earliest cockroach-like fossils are from the Carboniferous period between 354–295 million years ago. However, these fossils differ from modern cockroaches in having long ovipositors and are apparently the ancestors of mantids as well as modern cockroaches. Current evidence strongly suggests that termites have evolved, in turn, directly from true cockroaches. The first fossils of "modern" cockroaches with short ovipositors appear in the early Cretaceous. Mantodea, Isoptera, and Blattodea are usually combined by entomologists into a higher group called Dictyoptera.


[edit] Biology
Cockroaches are generally either scavengers or omnivores. The exception to this is the wood-eating Cryptocercus species found in China and the United States. Although they are incapable of digesting the cellulose themselves, they have a symbiotic relationship with a protozoan that digests the cellulose, allowing them to extract the nutrients. In this, they are similar to termites and current research suggests that the genus Cryptocercus is more closely related to termites than it is to other cockroaches. Cockroaches 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 Blatella germanica with oothecaFemale cockroaches 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.


Common household roaches
A. German cockroach, B. American cockroach, C. Australian cockroach, D&E. Oriental cockroach (♀ & ♂)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 a lifetime; in favorable conditions, it can produce 300-400 offspring. Other species of cockroach, however, can produce an extremely high number of eggs in a lifetime. Laying up to 100 eggs in each egg sac, it only needs to be impregnated once to be able to lay eggs for the rest of its life, allowing one single cockroach to lay over a million eggs during its lifespan.