Cockroaches
The 2 most likely cockroaches to be encountered in the UK are the
German and the Oriental Cockroaches. Although a few other species
could be encountered treatment would be the same.
Cockroaches have been great pests in domestic dwellings for centuries
and are always difficult to eradicate, largely because of their secretive
and nocturnal habits. They will only be seen occasionally during the
daytime, and the destruction of these does little to reduce the population.
They live during the day in cracks and crevices, behind tiles, in refrigerator
motors, junction boxes, light fittings etc. If cockroaches are seen regularly
during the day then the infestation is usually quite serious as they
are nocturnal. The 2 most likely cockroaches to be encountered in the
UK are the German and the Oriental cockroaches. Although a few other
species could be encountered, treatment remains the same. Cockroaches
are common in commercial premises associated with the production or handling
of food. Gregarious and nocturnal, they spend the day hiding in cracks
and crevices around such areas as sinks, drains, cookers, the backs of
cupboards and in refrigerator motor compartments. They especially favour
buildings with service ducts and complex plumbing installations. Infestations
may be introduced through incoming laundry, on raw materials, in crates
and packaging, or arise as the insects enter the buildings via such routes
as drains or refuse chutes.
German Cockroach
The adult is 10-15 mm long, yellowish-brown with wings well developed
on both sexes. The wings are never used. It is an excellent climber on
both smooth and rough surfaces. The female of the species produces 4-8
egg capsules at monthly intervals. Each capsule contains about 30 eggs,
which the female carries with her until just before hatching, which then
takes 2-4 weeks. Efforts are made to conceal the capsule near a food
source, where the nymphs will hatch and pass through 5-7 moults before
reaching maturity. At a temperature of 25C maturity is reached in 3.5
months, but this time is subject to great variation depending on the
temperature. Adults live approximately 8.5 months at 25C.
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The German cockroach is
particularly successful for the following reasons: the large number of
eggs per capsule. The female protects the egg capsule, by carrying it
until just before hatching. Short development period to hatching and
maturity. Small size, therefore readily conceals itself. The German Cockroach
prefers warm moist conditions (25-31C) such as occur in kitchens and
restaurants. For this reason it is sometimes known as the steam fly.
It moves quickly and climbs with ease, thus it will be found in harbour
ages on vertical and upside-down surfaces, in cracks and crevices, behind
panels and notice boards, in drawers and cupboards, inside electrical
equipment and machinery.
Oriental Cockroach Adult, 20-24 mm long, dark brown, nearly black. Wings of male cover
two-thirds of abdomen. Wings of female are vestigial and she cannot fly.
Both can climb rough but not smooth surfaces. The female produces 5 egg
capsules at monthly intervals. The thick walled resistant capsules, 12mm
in length, each contain up to 16 eggs and are cemented to the substrate
in the vicinity of a food supply, and may be covered over with debris.
Nymphs emerge 6-12 weeks later and progress through 7-10 moults before
reaching maturity, a process which takes 10 months to 2 years depending
upon temperature and food supply. Adults live approximately 4.5 months
at 25C. The slow proliferation of the Oriental cockroach will limit its
success where reasonable standards of hygiene exist. The Oriental cockroach
will tolerate lower temperatures than the German, but will tolerate higher
temperatures as long as water is available. It is largely being replaced
by the German, which is a better climber and faster breeder.
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