Eggs. The egg capsule of the German
cockroach is about 1/4 inch long. Each egg capsule
contains 30-40 eggs. Altogether, the female will produce
from four to eight capsules in her lifetime.
In all large infestations, there are egg capsules
present. Even if the cockroach population is eliminated,
as many as one in every twenty egg cases can still
Nymphs. The eggs hatch when the nymphs
inside create pressure that splits the case and allows
the young to escape. As they develop, they molt six
or seven times before reaching the adult stage. When
molting, nymphs are very soft and vulnerable.
Adults. Adult cockroaches emerge from
the last nymph as molt, fully winged. They join a nearby
aggregation made up of other adults and larger nymphs.
Behavior and Harborage
Cockroaches live in areas of high humidity and nearby
food. They will find harborage into which they can
fit closely. As the number of roaches increase and
favorable harborage is filled, roaches are forced to
leave the aggregation or remain in less favorable harborage.
They will find these new sites during their foraging
periods just before dawn and after dark.
do not respond to mating behavior for more than one
week after becoming adult. Proximity for mating is
especially important, as males and females have to
touch antennae and exchange sex pheromones to initiate
mating. After mating, females feed intensively for
several days, then seek secure hiding places where
they can be safe with their egg capsules.
Such seclusion means that females with egg capsules
feed less frequently and are exposed to pesticides
less often. Clients often report seeing no adult roaches
after a technician's last treatment, but later observe "little
black ones". The client is reporting the success
of the females with egg capsules that were deep in
harborage and did not come in contact with superficially
or inexpertly applied pesticides.
foraging pattern of German cockroaches is much less
random that one would expect. The roaches leave their
refuge and usually go to the first perpendicular surface
they find, where they stop, turn, and move along the
intersection of the two surfaces (usually a floor and
a wall). As one can imagine, food crumbs often wind
up in the same places, that is in wall moldings, corners
made by walls, stoves, counters, canisters, etc.
The most convenient hiding places, in and around refrigerators,
stoves, under sinks, and undisturbed cabinets, provide
both protection and food. The most favorable humidity
level is found in kitchens with sink traps, leaking
faucets, standing water, wet sponges, etc. A bathroom
is popular because of its toilet bowls, sinks, wet
wash cloths, and sometimes, water heaters. While there
is less food in bathrooms, food areas are usually nearby
or available through holes around plumbing pipes. These
pipes provide additional refuge and areas for population
expansions into adjacent rooms or apartments.
In areas of great infestation, German cockroaches
can build up outside heavily infested apartment units
in the summer. Most often, outdoor infestations are
found only outside the structures from which steady
roach migrations occur and near dumpsters and garbage