Wood Cockroaches

Origin: Apparently the German roach originated in Africa, but was transported through early commerce to Europe and now is found throughout the world.

Biology: The German roach is a nocturnal animal, strongly avoids light, cannot fly, and in almost all situations will be found indoors. Infestations normally begin by the introduction of roaches in packages. The biological potential of this species is enormous, with females producing an average of 5 egg capsules in their lifetime, each with an average of 30 eggs in it. The time from egg to mature adult averages about 3 months, allowing 4 generations of the insects each year. Female adult roaches live for about 200 days. Females carry the egg capsule until one day before the eggs are to hatch, providing necessary moisture into the eggs. Her activity level is low while she is in this “gravid” stage. This species has a higher moisture requirement than many other species, and is most likely to be living near moisture sources and in humid areas. First instar nymphs often remain in hiding, feeding on the fecal material of other roaches. Older roaches are extremely variable in their diets, feeding on virtually any materials in a food environment. They may also nibble on human hair or finger and toenails.

Identification: The German roach is typical of the genus Blattella, with a tan to brownish color, small size, and two dark, longitudinal stripes on its prothorax. Adults reach about ½ inch in length, with wings that reach the end of the abdomen in females and just beyond the tip of the abdomen in males. Neither is capable of flight. Nymphs begin as extremely small insects and without any hint of wings. However, they do have the dark markings on the prothorax. This species may be distinguished from the Field roach by the color of the face, which is light brown in the German.

The feeding damage of cockroaches is primarily done by the large species, such as the American, Australian, and the oriental roach. The American roach is probably responsible for most of the feeding damage on book covers and paper products. Large roaches have strong, chewing mandibles and bite off bits of cover and paper.
The feeding damage of large roaches is ragged in appearance and often begins at the edges of magazines and paper products. With repeated bites, large, excavated, ragged holes and depressions will result. The feeding on book covers resembles mold at a distance, but when viewed close-up, it is easy to see a puckered effect on the cover as individual bites have been taken out of the cover by the roaches. Large, irregular patches of feeding damage occur on covers and spines. Cockroach feeding will often remove the surface layer and begin to break into the fibers of the cloth cover. With leather covers, the feeding may commence all the way to the backing.
American roaches leave other signs and evidence while feeding on books and paper products. They regurgitate a brown liquid called attar while feeding and resting on materials.
This attar, which contains chemical pheromones that act as an attractant to other cockroaches, is called an aggregation pheromone. Often smears and tear-shaped droplets of this brown liquid will be left behind (on books and library materials).
American roaches may leave behind pelletized excrement on or around the products on which they are feeding

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