This is the other cockroach which is arguably the most common in the
U.K. but I would say that it all depends where you are in the country.
Again they are found in the same places as the common cockroach, with
one exception, these boys can walk across ceilings. Yep..!! better
check that cup of tea just to see if there is anything floating in it.
The other difference with this species is that the female carries the
egg case (Oothecae) around with her until it is just due to hatch whereas
the common cockroach is just that and dumps hers after a few hours.
This insect was introduced from N.Africa. Both sexes can fly but
are reluctant to do so. They are also sometimes called 'Steam
The German cockroach is light brown
with two dark longitudinal stripes on the thorax. Adults are about 5/8-inch
long and both sexes have fully developed wings. The number of eggs in
the ootheca varies from 18 to 50 with a mean of 32, and the female carries
the ootheca until shortly before hatching. Female German cockroaches
may occasionally help the nymphs emerge from the egg capsule.
The average life cycle takes 60 days
at room temperature. The German cockroach is the species most commonly
found in households for several reasons: (1) it has a larger number
of eggs per capsule, (2) nymphs reach sexual maturity more quickly than
other cockroaches, (3) the female carries the egg capsule and protects
the embryos until hatching, (4) German cockroaches are small and can
conceal themselves easily, and (5) they can rapidly build up resistance
to insecticides. This species is very active.
Both sexes are fully winged although
they rarely fly. They're often carried from place to place in items
such as bagged potatoes and onions, bottle cases and cartons and food
packages. They travel readily from one location to another and pass
through very small openings.
Places where German cockroaches are
found often share many common characteristics; they'll usually be warm,
dark, and have small cracks and crevices or other small openings into
dark confined areas. Such places will generally be rather moist or located
near water sources and food supplies.
German cockroaches usually cluster closely
together. Adult female cockroaches with oothecae are found deeper within
a harborage than other life stages. This makes it extremely difficult
to eliminate this species unless extreme care is taken in thorough pesticide
treatments. In populations which have developed pesticide resistance,
individuals may scatter widely throughout a building. Although German
cockroaches are normally most active at night in dark areas, people
may see them out of their normal hiding places wherever they aren't
few interesting facts:-
let's do a theoretical calculation based on the facts above:-
- These guys are 12 - 15 mm
- They are coloured light brown
with two dark stripes on the thorax.
- The wings are as long as
the body, and overlap in both sexes.
- The oothecae is carried by
the female until hatching is imminent.
- This young lady produces
4 - 8 oothecae in her lifetime.
- In this species, the oothecae
contain 35 - 40 eggs.
- The hatching time is only
- The nymph achieves adulthood
in 5 - 7 moults, remember cockroaches don't pupate.
- The nymphal development can
be as quick as 6 weeks, but can take up to 6 months.
us assume that the first female lays 1 oothecae, this will give us 40
eggs for arguments sake.
Say that there is plenty of food about and nymphal development is completed
in 8 weeks and that 50% of these nymphs turn out to be females, let's
say 20 females.
These females then lay 1 oothecae each.
This will give us 20 times 40 eggs which is 800.
Again there is plenty of food about and nymphal development is 8 weeks
and again 50% are females.
These females lay 1 oothecae each.
This gives us 400 times 40 which is
So after 9 months we have got
sixteen thousand cockroaches,
assumes that none would die in development (mortality rate) but it does
not take into account the fact that the original cockroaches would still
be laying further oothecae and that these would be hatching and maturing.
There is of course a high mortality rate probably about
90%, and a good job too, but even so, if an infestation is not controlled
it can very soon get out of hand.
ootheca containing 35-40 nymphs
to main Cockroach page