Cockroaches
Cockroaches are among the oldest creatures on earth. Fossils not
so different from modern cockroaches have been found in 250 million
year old rocks. They are also ubiquitous; though originating in hot
climates they are now found everywhere. In cooler climates they
live predominantly inside warm human habitations. A survey of local
authorities in England and Wales in 1993 found that over 80 per
cent of authorities had infested premises. More than 60 per cent of
hospitals are infested.
Cockroaches are large, robust insects with whip-like antennae
and two pairs of wings. The most common species in Britain are
German and Oriental cockroaches; Brown-banded and American
varieties are also found (the names have little real bearing on the
origin of the insects). Adult cockroaches live about 4-14 months,
during which time females can produce up to 50 oothecae (egg sacs).
Each ootheca contains 12-30 eggs. A female German cockroach would
produce about 150 live offspring in an average 8 month
lifetime.
Cockroaches like
- concealment
- comfortable temperature
- food and moisture
- society
Cockroaches like to avoid daylight and hide in cracks and
crevices, known as harbourages. They eat almost anything, including
cardboard, and come out to forage at dusk and early night. They
thrive at temperatures of 20-35°C, more towards the higher end of
the range. They need access to water. They stay together in groups.
They are mostly found in kitchens and toilets, for
example behind cookers, in laundry baskets, at the backs of
drawers or behind peeling wallpaper. They move along water pipes
and air ducts.
Tower blocks are particularly vulnerable to infestation because
of the ease with which cockroaches can move through the building.
The design of buildings and the materials used in their
construction can facilitate the spread of cockroaches. Cockroaches
can walk, run, jump and sometimes fly. But probably their main
movement from building to building is in transported goods; this
can even occur in ships and aircraft.
Cockroaches and disease
There is a possibly apocryphal story of the effects of
cockroaches in a clean but overcrowded dwelling where a large
number of children occupied a single bedroom. it was observed that
none of the children had eyebrows and it was discovered that
cockroaches were feeding on the eyebrows while the children slept,
there being no other source of food available.
Whether or not this story is true, cockroaches are implicated in
the transfer of disease. They are bearers of pathogens such as
salmonella and staphylococcus. They have been associated with
outbreaks of gastroenteritis, typhus and skin diseases. They taint
human food. They are a particular menace in hospitals.
Contact with cockroaches can lead to a number of allergic
illnesses, including dermatitis, urticaria (another skin disease),
rhinitis, bronchitis and asthma. Laboratory workers involved in the
breeding of cockroaches for research are particularly prone to
these conditions.
Some people have an aversion to cockroaches amounting to phobia
and can suffer anxiety when in the presence of the insects.
Keeping cockroaches out
Cockroaches are vermin which should be denied access or which
should be eradicated if they obtain access.
Good hygiene is essential in preventing or limiting infestation.
it is vital to deny cockroaches food, water and shelter. Dishes
should be washed promptly, food stored in tightly sealed
containers, working surfaces kept clean, and all scraps and crumbs
cleared up. Rubbish should be kept in containers with tight lids
and the bags properly sealed when moved outside. Water spills
should be mopped up and all water leaks, sweating pipes, etc.
repaired. Remove any clutter where cockroaches might live and mend
any holes and cracks in walls. Seal openings around pipes, remove
paint and loose wallpaper and replace broken tiles.
Insecticides and other treatments
Eradication of an infestation is a professional job, if complete
and permanent removal of cockroaches is to be achieved. Some of the
older insecticides can be purchased by members of the public but
more modern and effective chemicals are only available for
professional use. Insecticides are toxic and present a risk to the
user unless properly employed. Once cockroaches have appeared in a
block of dwellings, treatment is needed throughout the block to
bring about eradication. Both home owners and tenants should report
the presence of cockroaches to the local authority Environmental
Health Department in Carlisle.
Eradication begins with trapping and monitoring. Traps are open
cardboard boxes placed near harbourages, coated on the inside with
adhesives, and containing bait which consists of food mixed with
insecticide. For blocks of flats, a representative selection of
flats (say 15-20 per cent of the total) needs to be chosen. The
number of cockroaches trapped indicates the extent of
infestation.
Taking action
Residents' and tenants associations have a vital role to play in
dealing with cockroach infestation by
- Educating their members about cockroaches by leaflets, posters
and public meetings.
- Persuading their members to agree to access to dwellings for
trapping, monitoring, and pesticide application.
- Bringing pressure to bear on councils to ensure eradication
programmes are implemented.
- Ensuring that the pesticide and application method and
frequency are not dangerous to people.
Councils are able to take action under the Public Health Act
1936 to obtain access to premises and carry out treatments. Council
officials must obtain a warrant from a magistrate and can enter at
24 hours notice.
The cockroach population increased rapidly in the 1980s but it
is now possible that it is being held in check, though no-one
really knows. However the combination of public demands for action
and the advent of more effective eradication methods do provide an
opportunity to bring this major public health hazard under
control.