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German Roach
  
 
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COMMON NAME: German cockroach
SCIENTIFIC NAME: Blattella germanica (Linnaeus)
CLASS I ORDER I FAMILY: Insecta / Blattodea l Blattellidae
METAMORPHOSIS: Simple
INTRODUCTION: The German cockroach is by far the most economically important and usually the most common of the cockroaches. In addition to being a nuisance, it has been implicated in numerous outbreaks of illness, the transmission of a variety of pathogenic organisms including at least one parasitic protozoan, and allergic reactions in many people. This species has worldwide distribution. In severe infestations, I have noticed, on several jobs a distinct odor or smell produced by the fecal matter that homeowners become used to and can not even notice the odor is present.
RECOGNITION: Adults about 1/2-5/8" long. Color light brown to tan except for 2 darker, almost parallel longitudinal stripes / bars / streaks on the pronotal shield. Female is darker than the male, her abdomen broader. They rarely glide or fly.
German cockroach nymphal instars 1-2 have their thorax colored dark brown to black but with pale lateral margins. Meso- and metathorax are pale/white throughout the central portion but have a continuous dark stripe near each margin. The thorax and abdomen are light brown ventrally. Later instars (from the 3rd on) have 2 dark longitudinal stripes on the pronotum and continuous with a dark abdomen. The abdominal segments usually have central areas pale on the dorsum.
German cockroach otheca or egg capsule is yellowish brown but generally two-toned, paler end attached to female. The capsule is about 1/4-3/8 long, with the length being more than twice the width. Sub-divisional furrows extend over the entire width; furrows are slightly bowed or arched; and have up to 20 eggs on each side.
BIOLOGY: The female cockroach carries her ootheca until it is within a couple of days of hatching, then she deposits it in a sheltered area or site. On the average, the female will produce about 5 oothecae, averaging up to 40 eggs each.
Developmental time for the cockroach (egg to adult) can takes up to 200 days, averaging about 100 days; under ideal lab conditions of 80°F and 40% relative humidity, the time is usually only 55 days. This means that usually 3 to 4 generations per year are produced, but up to 6 are possible. Adults live from 100-200 days. Established / mature German cockroach populations are typically composed of at least 75% nymphs.
HABITS: German cockroaches are found throughout structures but show a preference for warm (70°F), dark 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. First instar nymphs require a crack of about 1/32 whereas, adults require a crack of about 3/16 in width.
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, VCR's, microwaves, etc. They have been observed to migrate from building to building on warm evenings, but this rarely occurs. Although uncommon, they can survive outdoors during the warm months.
Members of the German cockroach family will feed on almost anything with nutritive value including all kinds of food, and such things as soap, glue, and toothpaste. Activity periods vary with life stage, age, and physiological state. For instance, reproducing females are quite active whereas, gravid (with ootheca) females are relatively inactive starting about the 5th day after mating and go only to food and water when necessary. Most males spend most of their time in harborage, even at night. All nymphs become immobile and stay in their harborage during the last few days of each instar while they prepare to molt. Therefore, for about 1/3 of the time the cockroach nymphs will not be found or found exposed during an inspection.
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