Tuesday, August 26, 2008

Cockroaches - German Cockroach

The German Cockroach is the most economically important urban pest. It is the most common cockroach species in houses, apartments, restaurants, hotels and other institutions throughout the United States. Adults are pale to medium brown and about 1/2 to 5/8-inch long. German cockroaches can be distinguished by the two dark stripes on the pronotum (head). Adults of both sexes have well developed wings, but they never fly. German cockroach nymphs resemble the adults except that they are smaller, wingless, and darker in color, often being nearly black.Adult females carries the egg capsule (ootheca) protruding from the rear of the abdomen until the eggs are ready to hatch. The egg capsule carries 48 eggs. Gestation is 20 to 30 days.

As mentioned previously, the German cockroach is the most commonly encountered of the house infesting species in the United States. It is also generally the most persistent and difficult to manage. If you think setting off a few bombs will get rid of this guy, you better think twice about calling an exterminator. The reasons for this are somewhat complex. First the German cockroach has a larger number of eggs per capsule than the other species that infest structures. Second, it also has the shortest period to develop from hatching until sexual maturity, so the population of German cockroaches will build up faster than those of other species.

Third, German cockroach nymphs have a better chance of surviving than do those of other species, because the female carries the egg capsule during the entire time that the embryos are developing within the egg. This results in the nymphs avoiding many hazards of the environment that may affect eggs that remain detached and isolated prior to hatch. Fourth, German cockroach nymphs are smaller than those of most other cockroaches, so they are able to conceal themselves in many places in accessible to individuals of the larger species. Moreover, several additional factors have contributed to the success of the German cockroach. Insecticide resistance is extremely quick in German cockroaches, and coupled with the high reproductive rates the resistant cockroaches are able to pass on this resist trait to their offspring.

The German cockroach is a general feeder but is particularly attracted to fermented foods and beverage residue (beer spills). If water is present adults can live a month without food, but young nymphs will die of starvation with 10 days. Without food or water the adult dies in less than two weeks. Infestations are sometimes found in areas not generally suspected of harboring German cockroaches, such as dresser drawers or in bedrooms. German cockroaches found scattered through non-food areas of a home or building is usually a sign of a very heavy infestation.

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