Common Name: German cockroach
Scientific Name: Blattella germanica
Introduction
The German cockroach does not actually originate from Germany but from Asia. It is by far the most important and usually the most common of the cockroaches. In addition to being a nuisance, it has been implicated in outbreaks of illness, the transmission of a variety of pathogenic organisms including at least one parasitic protozoan and allergic reactions in many people. The German cockroach has worldwide distribution.
Recognition
Adult German cockroaches measure 1/2 to 5/8 of an inch long. They are light brown to tan except for 2 dark, parallel stripes on the pronotal shield (the back, behind the head). Females have a broader abdomen than males. These cockroaches are not good fliers but use their wings like a parachute to break a fall. The nymphs have 2 dark brown to black stripes on their tan thorax, similar to adults and have a dark abdomen.
The egg capsule (ootheca) is yellowish-brown, measures 1/4 to 3/8 of an inch long, is nearly three times longer than wide, has subdivisional furrows extending its entire width, is slightly bowed or arched and contains 30 to 40 eggs.
Biology
The female carries her egg capsule until it is within 1 to 2 days of hatching and then deposits it in a sheltered area. On the average, the female will produce about 5 egg capsules (range 4 to , averaging 30 to 40 eggs (range 18 to 50) each.
Habits
German cockroaches are found throughout structures but show a preference for warm (70ºF) and humid places. They are usually found in kitchens and secondarily in bathrooms, but infestations often occur in rooms where people eat and drink while watching television such as the den, bedroom, etc. Any crack or crevice located near a source of food and/or water is prime harborage and they spend about 75% of their time in such harborages.
These cockroaches are most commonly introduced into buildings via paper products or paper packaging such as grocery bags, cardboard boxes, drink cartons and via secondhand appliances such as refrigerators, televisions, VCRs, boomboxes, microwaves, etc. They have been observed to migrate from building to building on warm evenings, if spaced closely together. Although uncommon, they can survive outdoors during the warm months.
Activity periods vary with life stage, age and condition. For instance, reproducing females are quite active whereas, gravid (ootheca-hearing) females are relatively inactive starting about the 5th day after mating and go only to food and water when necessary. Males spend most of their time in harborages, even at night. All nymphs become immobile and stay in harborage during the last 3 days of each instar while they prepare to molt. Hence, about 1/3 of the time the cockroach nymphs will not be found exposed during an inspection.
