German Cockroach
Introduction
The German cockroach is by far the most important and is 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. This species has worldwide
distribution.
Recognition
Adults are about 1/2-5/8 inch long. Color light brown to tan except for two
dark, almost parallel longitudinal stripes on pronotal shield. Female
darker than male, her abdomen broader. Rarely glide or "fly."
Nymphal instars one to two with thorax dark brown to black but having pale
lateral margins, meso- and metothorax pale/white centrally but with a
continuous dark stripe near each margin; thorax and abdomen light
brown ventrally. Later instars with two dark longitudinal stripes on
pronotum continuous with dark abdomen, and abdominal segments usually
with ventral areas pale on dorsal.
Ootheca or egg capsule yellowish brown but usually low-toned, paler
end attached to female; about 1/4-3/8 inch long, with length more than
twice width; subdivisional furrow extending entire width; slightly
bowed or arched; and with about 15-20 eggs on each side.
Habits
German cockroaches are found throughout structures but show a
preference for warm and humid places. They usually are 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 percent of their
time in such harborages. First instar nymphs require a crack of about
1/32 inch whereas, adults require a crack of about 3/16 inch in width.
These cockroaches most commonly are introduced into buildings via
paper products or paper packaging such as grocery bags, cupboard
boxes, drink cartons, and via secondhand appliances such as
refrigerators, televisions, VCRs, microwaves, etc. They have been
observed to migrate from building to building on warm evenings, but
this rarely occurs. Although it is uncommon, they can survive outdoors
during the warm months.
They feed on almost anything with nutritive value including all kinds
of food, and things such as soap, glue, and toothpaste.
Activity period varies with life stage, age, and physiological state.
For instance, reproduction females are quite active, whereas gravid
females are relatively inactive starting about the fifth day after
mating and go only to food and water when necessary. Males spend most
of their time in harborage, even at night. All nymphs become immobile
and stay in harborage during the last three days of each instar while they
prepare to molt. Hence, about 1/13 of the time the cockroach nymphs will
not be found or found exposed during an inspection.
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