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Cockroach, Roach, Blattidae
Oriental cockroach, American cockroach

Insects of the family Blattidae, are commonly known as cockroaches. They form the old group Cursoria, or runners. As a rule, the body is oval and flat, with all legs being similar in form. Roach heads are deflected or bent under and generally concealed by the prothorax (forward section of the thorax). Their hind wings are slightly folded.

The exact origin of the common name "cockroach" hasn't been determined, but there are several similar sounding words in other languages. In fact, the title of the Spanish language folksong popular in Mexico, "La Cucaracha," sounds a little like, and translates literally to, "The Cockroach." The Dutch word for cockroach, "kakkerlak," also sounds somewhat similar to the same in English.
American cockroach, Periplaneta americana
American cockroach, Periplaneta americana
American cockroach, Periplaneta americana
American cockroach, Periplaneta americana
American cockroach, Periplaneta americana
American cockroach, Periplaneta americana
The insects of this group are very abundant in the tropics, but several species have become “domesticated” and are abundant in colder parts of the world. Cockroaches are very persistent, and insects of this family existed in great numbers in geologic periods prior to the Tertiary. Fossils are found in considerable number in Carboniferous rocks, and one form has been found in Silurian sandstone.
Cockroach eggs are laid in cases, as with the Mantidae, and the cases of common roaches are kidney-shaped. Most cockroaches are nocturnal in habit. They feed on a great variety of substances. This is especially true of those which inhabit houses. Their natural food is primarily dead animal matter.

Only a few of the thousands of cockroach species in the world cause problems for humans. Of these many species, common ones in American households would include the American cockroach, Periplaneta americana, the German Cockroach or "croton bug," Blattella germanica, formerly Ectobia germanica, and the Oriental cockroach, Blatta orientalis. In addition, the Australian cockroach, Periplaneta australasiae, and the Asian cockroach, Blattella asahinai, can be found in southern U.S. states such as Florida.
Oriental cockroach, Blatta orientalis, Shad roach
Oriental cockroach, Blatta orientalis
Females carry their egg case until they find a proper place to leave it or until the eggs are nearly ready to hatch. Young roaches grow slowly and pass through a variable number of molts, sometimes as many as ten. The time required for the development from the egg to the adult may be prolonged by low temperature or shortage of food. The German cockroach has been shown to reach adulthood in as short as four and one-half months; while the American cockroach has been raised from egg to adult in roughly a year.
Oriental cockroach, Blatta orientalis, Shad roach
Oriental cockroach, Blatta orientalis
Oriental cockroach, Blatta orientalis, Shad roach
Oriental cockroach, Blatta orientalis
Most of our native cockroaches are outdoor feeders and exceptionally clean insects. Cockroaches can be observed grooming frequently, licking their legs and antennae, much like a housecat cleans its coat. By doing this, they keep their external sensory hairs primed to detect other roaches, predators, but more importantly, food and water. Their survival depends on it. However, what's clean to a cockroach would hardly be considered clean by human standards. Roaches venture into sewers where they can pick up and transmit many kinds of disease organisms directly to our exposed food.
Oriental cockroach, Blatta orientalis, Shad roach
Oriental cockroach, Blatta orientalis
Oriental cockroach, Blatta orientalis, Shad roach
Oriental cockroach, Blatta orientalis
The cockroaches mentioned here are practically “domesticated animals” in so far as they have accommodated themselves to the environments of civilization. Roaches will eat almost everything, animal or vegetable in origin, and they are top ranking household pests. Cockroaches are quite cosmopolitan having been carried in ships to almost all parts of the world.
A roach's digestive tract may contain any number of pathogens, or germs, depending on what their last meal was. They may have eaten a bacteria-loaded decomposing carcass right before heading to your cupboard. In this case they'll more than likely release the same germs on or around your food and packaging via their excrement and tiny footprints.
Oriental cockroach, Blatta orientalis, Shad roach
Oriental cockroach, Blatta orientalis
Cockroaches are fond of dark, humid places. They thrive in and around water pipes, walls and cupboards. They thrive where even the smallest amount of crumbs exist. Roaches roam around houses at night in search of meals. Even new homes can be stocked with roaches through their nighttime migrations from over-supplied adjoining structures. One dark day, an army of cockroaches was seen crossing the street from an obviously less than spotless restaurant. They headed toward a new frontier in the buildings opposite. Most of them were females, carrying egg cases!
Nuclear Cockroaches?!
A final interesting topic to discuss would be cockroaches vs. "the bomb", or the notion that roaches would inherit a post nuclear apocalyptic earth from a vaporized human race. Across a population, insects are more robust than mammals in terms of radiation survivability. The reason for this revolves around cell division. Insects and other arthropods growth include molting cycles. As these animals grow larger, they shed their outer skins, or molt. During each molt cockroach cells typically divide once. Cells of any species are most sensitive to radiation damage at the time of their division. Cockroaches molt once per week at most, and the process typically lasts for 2 days. Therefore at any one given time, 3/4 of the cockroach population would not have cells in a state most sensitive to radiation. Humans on the other hand, have blood and immune stem cells that are constantly dividing, making them sensitive to radiation all the time. Not only this, but what would be considered a lethal dose of radiation to a cockroach is many times higher than that of a human. So in comparison to humans, the cockroach would be more durable against a radioactive nuclear catastrophe.

Andy Williams / CritterZone.com
The cockroach pictures on this page are available for commercial stock photography license. All text and photos that appear on this webpage are copyrighted and may not be copied or used in any way without permission from CritterZone.

This article references, in part, the published works of: Cockroach expert, Professor Joseph Kunkel, Biology Department, University of Massachusetts Amherst

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Giant South American cockroach, Blaberus giganteus
Giant South American cockroach,
Blaberus giganteus