Adult German cockroaches are 1/2 to 5/8 inch long and tan to light brown. Although they have fully developed wings, they do not fly. Nymphs are similar in appearance to adults except that they are smaller and do not have wings. The German cockroach is best identified by its small size and by two dark parallel lines running from the back of the head to the wings.
German cockroaches prefer a moist environment with a relatively high degree of warmth. They are usually found in kitchens (near dishwashers, stoves, and sinks) and in the bathrooms of homes. German cockroaches are mostly active at night, when they forage for food, water, and mates. During the day they hide in cracks and crevices and other dark sites that provide a warm and humid environment. Their relatively wide, flat bodies enable them to move in and out of cracks and narrow openings with ease. They may be seen during the daytime, particularly if a heavy population is present.
German cockroaches generally forage for food and water at night. Cockroaches are mostly scavengers and feed on a wide variety of foods. They are especially fond of starches, sweets, grease, and meat products. In many locations, garbage is a principal food source.
Life Cycle & Reproduction
German cockroaches have three developmental stages: egg, nymph, and adult. Females produce a light brown egg capsule that are less than 1/4 inch long. Each capsule contains up to 50 eggs, and adult females usually produce from four to eight egg capsules during their lifetime. Egg capsules are carried, protruding from the abdomen, until they hatch and are then deposited into crevices and other sheltered locations. The length of the egg stage varies from 15 to 35 days depending on conditions, with six to seven nymphal stages (instars) occurring over a period of 6 to 31 weeks. The life span of an adult varies from 20 to 30 weeks.
Cockroaches have been reported to spread at least 33 kinds of bacteria, six kinds of parasitic worms, and at least seven other kinds of human pathogens. They can pick up germs on the spines of their legs and bodies as they crawl through decaying matter or sewage and then carry these into food or onto food surfaces. Recent medical studies have shown that cockroach allergens cause lots of allergic reactions in inner city children. They were even shown to cause asthma in children.