The German cockroach 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. This species has worldwide distribution.
Adults about 1/2-5/8" (13-16 mm) long. Color light brown
to tan except for 2 dark, almost parallel longitudinal stripes/bars/streaks
on pronotal shield. Female darker than male, her abdomen broader.
Rarely glide or "fly".
instars 1-2 with thorax dark brown to black but having pale
lateral margins, meso- and metathorax pale/white centrally
but with a continuous dark stripe near each margin; thorax
and abdomen light brown ventrally. Later instars (3rd on)
with 2 dark longitudinal stripes on pronotum continuous with
dark abdomen, and abdominal segments usually with central
areas pale on dorsum.
or egg capsule yellowish brown but usually two-toned, paler
end attached to female; about 1/4-3/8" (6-9 mm) long,
with length more than twice width; subdivisional furrows extending
entire width; slightly bowed or arched; and with about 15-20
(range 925) eggs on each side.
(Adults only). (1) Asian cockroach (Blattella asahinai) with
almost identical color pattern, attracted to lights, flies
readily, breeds outdoors in leaf litter, presently known only
from Florida, identification should be confirmed by an expert.
(2) Brownbanded cockroach (Supella longipalpa) and Pennsylvania
wood cockroach (Parcoblatta pensylvanica) lack 2 dark longitudinal
stripes on pronotal shield. (3) Field cockroach (B. vaga)
with a median dark line between eyes on front of head. (4)
Other cockroaches are either smaller or larger, lack characteristic
pronotal stripes, and/or are not associated with structures.
The female carries her ootheca until it is within 1-2 days
of hatching, and then deposits it in a sheltered area/site.
On the average, the female will produce about 5 oothecae (range
4-8), averaging 30-40 eggs (range 18-50) each.
time (egg to adult) usually varies from 54-215 days, averaging
about 103 days; under lab conditions of 80 degrees F/27 degrees
C and 40% relative humidity, usually only 50-60 days are required.
This means usually 3 to 4 generations per year, but up to
6. Adults live about 100-200 days (range 1-303). Established/mature
German cockroach populations are typically composed of at
least 75% nymphs.
German cockroaches are found throughout structures but show
a preference for warm (70 degrees F/21 degrees C) 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" (1 mm) whereas, adults
require a crack of about 3/16" (5 mm) in width.
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.
feed on almost anything with nutritive value including all
kinds of food, and such things as soap, glue, and toothpaste.
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. Males spend most of their time in harborage,
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 or found exposed during an inspection.
Follow the standard control procedures but more frequent service
may be required because of their rapid reproductive rate.
At least 95% of the population must be eliminated on the initial
or clean-out service, or the typical maintenance program will
usually fail. Baits are particularly effective, but correct
placement along junctions and/or in cracks and crevices in
or near harborages is essential. Incorporating IGRs (insect
growth regulators) into the service helps with long-term control.
Be sure to follow label directions.