INTRODUCTION
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.
RECOGNITION
Adults about ½ - 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." Nymphal 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. Ootheca or egg capsule yellowish brown but
usually two-toned, paler and attached to female; about ¼-3/8"
(6-9mm) long, with length more than twice width; subdivisional
furrows extending entire width; slightly bowed or arched; and
with about 15-20 (range 9-25) eggs on each side.
SIMILAR
GROUPS
(Adults only) (1) Asian cockroach (Blattella asahinal)
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 (Supelia longipalpa) and Pennsylvania
wood cockroach (Parcoblatta pennsylvanica) lack 2 dark
longitudinal stripes on pronotal shield. (3) Field cockroach (B.
vega) 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.
BIOLOGY
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. Development 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 3-4 generations per year, but up to 6. Adults live
about 100-200 days (range 1-303). Establised/mature German cockroach
populations are typically composed of at least 75% nymphs.
HABITS
German cockroaches are found throughout structures but show a
preference form warm (70 degreeF/21 degree 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" (5mm) 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. They 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. 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 no0t be found
or found exposed during an inspection.
CONTROL
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. |