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 a full complement of eggs, but subsequent capsules can
contain less.
GERMAN COCKROACH
When the female goes into safe hiding, she takes
Blattella germanica
the capsule with her, reducing exposure to possible
The German cockroach is not only the cause of
harm. In extreme danger, she will detach the capsule
the largest number of phone calls requesting pest
and flee. The capsule has a relatively impervious
control, but also represents the largest number of
surface to protect its eggs. It does, nonetheless,
control failures of any household pest. It is most
receive moisture from or give moisture to the female.
successful at infesting human structures and
In extremely dry atmospheres, however, the female
withstanding pest control activity. Pest control
will abort the egg capsule. In all large infestations,
technicians will need to double their efforts in
there are egg capsules present. Even if the cockroach
analyzing every German cockroach infestation, and
population is eliminated, as many as one in every
should be prepared to use more than one technique to
twenty egg cases can still hatch.
Nymphs. The eggs hatch when the nymphs inside
bring the infestation under control.
create pressure that splits the case and allows the
Appearance
young to escape. They often will stay around the
Adult German cockroaches
opened egg capsule after hatching. Then, as they
develop, they molt six or seven times before reaching
are l/2 inch long or slightly
longer. Males are grayish-tan
the adult stage, Females often have one more molt
with two black stripes on the
than males. When molting, nymphs are very soft and
pronotum, and have a tapering
vulnerable.
abdomen. Females are usually
darker and their abdomens are
more rounded.
Nymphs are sometimes not
recognized as cockroaches; they
appear quite different than the
adults. After molting, they will
be ivory white for several hours before turning dark.
People who see them at this time often think they are
albino cockroaches. [Actually, such observations mean
that the cockroach population is so large, the nymphs
cannot find unoccupied spaces in which to hide and
molt, for they normally leave their aggregations to
molt in private.] In the first stage, nymphs are very
dark. In later stages, a pale tan stripe appears down
the middle from front to rear. This stripe divides the
German cockroach nymph
nymphal markings into two dark, long stripes. The
Adults. Adult cockroaches emerge from the last
stripes remain as two dark streaks on the adult's
pronotum, while the rest of the body is covered by the
nymphal molt fully winged. They join a nearby
tan or brown wings.
aggregation made up of other adults and larger
nymphs. The aggregation is held together by a very
short-range odor called the aggregation pheromone.
Life Cycle
Eggs. The egg capsule of the German cockroach
Behavior and Harborage
is about 1/4 inch long. Half of it protrudes from the
Aggregations of cockroaches live in areas of high
female's abdomen. It is carried in this way for three
humidity and nearby food. They will find harborage
weeks until it is dropped, about one day before the
into which they can fit closely. As the number of
eggs hatch. The drop usually takes place in a secluded
roaches increase and favorable harborage is filled,
portion of the infested habitat. [If the egg case is
roaches are forced to leave the aggregation or remain
dropped much more than one day before hatching
in less favorable harborage. They will find these new
time, the young die.] Each egg capsule contains 30-40
sites during their foraging periods just before dawn
eggs. Altogether, the female will produce from four to
and after dark.
eight capsules in her lifetime. Four capsules will have
Module One, Chapter 2, Pg 2
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