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Bed Bugs
Order: Hemiptera (‘half-winged’ true bugs)
Characteristics: Pairs of wings normally
present; mouth parts piercing and sucking, forming a beak, or rostrum,
normally held under the body. Metamorphosis usually incomplete, with egg
and nymphal stages.
Family: Cimicidae.
Flat, oval insects, with very short, functionless forewings; hindwings
absent; rostrum lies in a ventral groove; tarsi 3-segmented; exclusively
bloodsucking.
Species characteristics and host/habitat:
Common Bed bug (Cimex lectularius)
Adults, 5mm long; reddish-brown in colour, becoming purple after feeding;
well-developed antennae; prominent, simple eyes; feet clawed so can climb
rough but not smooth surfaces; ratio of head width (including eyes) to
length of third antennal segment usually greater than 1.7.
Host/habitat:
The principal host is man, though other warm-blooded animals can be parasitised.
Found in human habitations throughout the world.
Other blood-feeding bugs
Blood-feeding bugs, very similar in appearance to the Common bed bug,
can often be found infesting birds’ nests and bat roosts. In certain circumstances,
these bugs may invade houses and attack humans. They include:
Pigeon Bug (Cimex columbarius)
Very similar in size and appearance to the Common bed bug; can be distinguished
by the ratio of head width to length of third antennal segment, which
is less than 1.6 in most specimens.
Host/habitat:
Principal hosts are birds; mainly found in starlings’ nests, pigeon lofts
and poultry houses, but can attack man.
Martin Bug (Oeciacus hirundinis)
Similar in appearance to the Common bed bug, but smaller and more hairy.
Can be further distinguished by the following characteristics: when viewed
from above, the front margin of the prothorax is far less concave than
in the other species; the head width is also more than twice the length
of the third antennal segment.
Host/habitat:
Principal hosts are birds; often found in martins’ nests, but can attack
man.
DISTRIBUTION
As bed bugs cannot fly, they must either crawl or be passively transported
in clothing, or more probably in luggage, furniture, books and other objects
used as harbourages. Their ability to withstand many months without feeding
increases their chances of surviving such transportation and the insects’
very wide distribution throughout the world demonstrates their success.
Any household can be invaded by bed bugs, but it is likely that infestations
will only become established in premises with low standards of hygiene.
Bed bugs are therefore generally associated with poor, crowded and unhygienic
conditions.
Most bed bug infestations are to be found in domestic premises, usually
in the bedrooms. Both juveniles and adults live similar lives, hiding
away in cracks and crevices for most of the time and coming out at night,
usually just before dawn, to feed on the blood of their sleeping hosts.
Their hiding-places will be close to where their hosts sleep: in the bed
frame or the mattress, in furniture, behind the skirting, behind the wallpaper
-- anywhere that affords a dark harbourage during the daylight hours for
these nocturnal creatures.
The insect infestations occur particularly in areas of high population
density including hotels, hostels and holiday camps.
In temperate climates bed bugs reach their peak numbers towards early
autumn. At this time all stages in the lifecycle will be present. With
the onset of colder weather their activity decreases, egg-laying ceases
and development of the juvenile forms slows down.
Bed bugs overwinter mainly as adults, since the eggs and nymphs are more
susceptible to low temperatures and die out with the onset of winter,
unless in adequately heated premises.
The bird-feeding bugs, such as the Martin bug, will be found in the nests
of their hosts and follow a similar lifestyle to the Common bed bug. The
occasional problems of these species attacking humans are likely to stem
from abandoned nests built near to or inside houses. Nests in lofts or
under eaves would be a likely source if such an infestation were suspected.
SIGNIFICANCE
Bed bugs are not regarded as disease carriers, but their blood feeding
can cause severe irritation in some people, resulting in loss of sleep,
lack of energy and listlessness, particularly in children. Iron deficiency
in infants has resulted from excessive feeding by bed bugs. The bite often
gives rise to a hard, whitish swelling which distinguishes it from the
flea bite which leaves a dark red spot surrounded by a reddened area.
Different individuals react differently to bites, some gaining immunity.
Probably more important, however, is the distaste with which these insects
are regarded. Bed bug excrement gives a characteristic speckled appearance
to their harbourages, whilst their ‘stink glands’ confer a distinctive
and unpleasant almond-like smell on infested rooms. In addition, the very
thought of being preyed upon by such creatures is quite sufficient to
make most people take immediate action to control them. The bed bug may
even help to create slums by driving away householders with reasonable
standards of hygiene, leaving behind only those who are less concerned
with such matters.
It is interesting to note that many factors are helping to sustain existing
bed bug populations: modern building techniques, which allow easy access
between adjoining properties; the increased use of central heating, which
allows continued feeding and proliferation during winter; the movement
of furniture in the second-hand market, which aids their distribution;
all these serve to maintain population levels.
LIFE-CYCLE
Bed bug eggs, which are slightly curved, measuring 0.8-1.3mm long by 0.4-0.6mm
broad, are cemented to the surfaces of the harbourages, often in large
numbers. Unhatched eggs are an opaque, pearly white colour, whilst hatched
eggs, which remain in position long after hatching, are opalescent and
translucent. While temperature and the availability of food have a profound
effect on egg production, under optimal conditions egg-laying is almost
continuous, at a rate of about three per day. The number of eggs laid
by a female in the course of her adult life has been variously quoted
as between 150 and 345.
The first-stage nymphs which hatch from the eggs are just over 1mm long
and, like all the nymphal stages, appear very similar to the adults, except
in size and colour. Early instars tend to be more amber than the darker
brown of the adult. Each nymph requires one full blood meal before moulting
to the next stage. Though there are variations in size, due mainly to
the effects of feeding, which may increase the bug’s weight by up to 6
times, the approximate lengths of each of the five nymphal stages are:
stage I 1.3mm, II 2.0mm, III 3.0mm, IV 3.7mm and V 5.0mm. The rudimentary
wings appear in the last moult.
The speed of development from egg to adult and the duration of adult life
vary according to temperature and availability of food. With frequent
feeding, at normal room temperatures (ca. 18-20°C) adults live for 9-18
months, with egg incubation taking 10-20 days and the complete cycle 9-18
weeks. Under these conditions nymphs feed at about 10-day intervals and
the adults weekly. If necessary, both can survive long periods without
food. Under cool conditions (13°C) starved adults could survive for as
long as one year.
In unheated rooms where the temperature drops below 13°C in the winter,
egg laying, moulting and feeding stops and the population declines as
eggs and young nymphs die. Under such conditions there is only one generation
per year. Where temperatures do not fall so dramatically, breeding may
continue throughout the year and two generations can be attained.
CONTROL
In all infestations, particularly those newly established in well-kept
houses, an attempt should be made to determine the source of infestation,
so that proper measures can be taken.
A thorough inspection of infested premises should also seek to uncover
the extent of the infestation, since the measures necessary for control
will depend on whether the infestation is established and widely distributed
throughout the premises, or recently introduced and likely to be more
localised.
Control measures used must be thorough and be directed at all the harbourages.
In circumstances where the infestation has originated from birds’ nests,
it will be necessary to treat the nests and advisable to birdproof the
building.
a) Hygiene/management
High standards of hygiene and house-keeping are unlikely to provide an
adequate method of control, but will reveal the presence of bed bugs at
an early stage, making control easier. Bed bugs can only proliferate if
they are tolerated. If they are suspected, a close inspection of the bed,
the mattress around the seams, the back of the headboard, etc., should
reveal their presence. The use of a pyrethroid-based aerosol sprayed lightly
around these areas may help, as the insects will be driven out of their
hiding places. The finding of eggs or egg cases and the blackish spots
of bug excrement will also indicate their presence. Infested bedding (e.g.
sheets) and clothing should be laundered or burnt and the fabric of infested
rooms thoroughly cleaned. Particular attention should be paid to removing
dust, fluff and debris from insect harbourages eg cracks, crevices, seams
of fabrics, buttons on mattresses etc.
b) Insecticidal control
To eradicate the infestation it will be necessary to treat the premises
thoroughly with suitable insecticides, including the beds, other furniture
and harbourages in the fabric of infested rooms. A professional pest control
organisation should be used, as the detection and thorough treatment of
all bed bug hiding places is a job which requires experience.
Glossary of terms
Instars: Any stage in an insects life cycle, especially between
moults. Prothorax: First thoracic segment. Rostrum: Beak
or snout. Tarsus (Tarsi): Apical section of leg (the foot).
ADVICE
Valent BioSciences has an extensive range of products specifically formulated
for the control of flying and crawling insect pests.
Further information on all Valent BioSciences' household insecticide products
is available from:
Valent BioSciences Corporation
870 Technology Way
Suite 100
Libertyville, IL 60048
The greatest care has been taken to ensure the accuracy of the information
contained in this Fact Sheet. Under no circumstance, however, will Valent
BioSciences Corporation be liable in respect of any error or omission.
© Copyright Valent BioSciences Corporation 2001
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