1. Fact Sheet Medical Entomology
Institute of Clinical Pathology and Medical Research Department of Medical Entomology
Bed Bugs
Introduction for nutrition and development. After clothing, bedding and furniture. As
Bed bugs were once a common mating, each female lays 2-3 eggs a such, they have a worldwide
public health pest worldwide, which day throughout her lifespan. The distribution.
declined in incidence through the cream coloured eggs (1mm in
mid 20th century. Recently length) are cemented on rough
however, bed bugs have undergone surfaces of hiding places, and will
a dramatic resurgence and hatch within around 10 days at
worldwide there are reports of room temperature, but longer in
increasing numbers of infestations. cooler conditions.
Australia has also been included in
this trend and the Department of The mouthparts of bed bugs are
Medical Entomology, ICPMR, has especially adapted for piercing skin
been at the forefront of and sucking blood. Like most blood
documenting this phenomena and sucking arthropods, they inject
providing information on the saliva during feeding, which has
ecology and control of this anticoagulant properties. Bed bugs
important public health pest. respond to the warmth and carbon
dioxide of a host and quickly locate
a suitable feeding site. They tend The Common Bed Bug,
Natural History Cimex lectularius ~5mm
not to live on humans and the only
Bed bugs are wingless insects,
contact is for a blood meal. Most
roughly oval in shape, 4-5mm long Clinical Presentation
blood feeding occurs at night, and
when fully grown, and are fast Skin reactions are commonly
they generally seek shelter during
runners. They are rust brown in associated with bed bugs, which
the day and become inactive while
colour and change to a deeper red result from the saliva injected
digesting the blood meal. However,
brown following a blood meal. Bed during feeding. Some individuals
bed bugs are opportunistic and will
bugs are dorsoventrally flattened however, do not react to their bite,
bite in the day especially if starved
and being thin means that they can whereas others note a great deal of
for some time. They can survive for
hide in narrow cracks and crevices, discomfort often with loss of sleep
long periods without feeding. While
making detection often very from the persistent biting. The most
their preferred host is human, they
difficult. commonly affected areas of the
will feed on wide variety of other
warm-blooded animals including body are the arms and shoulders.
The two main species that bite Reactions to the bites may be
rodents, rabbits, bats, and even
humans include the common bed delayed; up to 9 days before lesions
birds.
bug, Cimex lectularius, and the appear. Common allergic reactions
tropical bed bug, Cimex hemipterus. include the development of large
Being a cryptic species, bed bugs
The presence of the former species wheals, often >1cm, which are
shelter in a variety of dark locations,
has been long known in Australia, accompanied by itching and
mostly close to where people sleep.
whereas the tropical bed bug was inflammation. The wheals usually
These include under mattresses,
only recently recognised in the subside to red spots but can last for
floorboards, paintings and carpets,
country by the Medical Entomology several days. Bullous eruptions have
behind skirting, in various cracks
Department, ICPMR. been reported in association with
and crevices of walls, within bed
frames and other furniture, and multiple bed bug bites and
There are five juvenile stages anaphylaxis may occur in patients
behind loose wallpaper. Bed bugs
known as nymphs, which are with severe allergies. In India, iron
tend to stay in close contact with
miniature versions of the adults in deficiency in infants has been
each other and heavy infestations
appearance. Each nymphal stage associated with severe infestations.
are accompanied by a distinctive
requires at least one blood meal to It has been suggested that
sweet sickly smell. Blood spotting
moult to the next stage and it takes allergens from bed bugs may be
on mattresses and nearby
5-10 minutes for complete associated with asthmatic reactions.
furnishings is often a tell tale sign of
engorgement to occur. The entire Bed bugs have been implicated in
an infestation.
nymphal development takes 6-8 the transmission of a wide variety of
weeks, while the adult bed bugs infectious agents, although their
Bed bugs are one of the great
can live on average for 6-12 status as vectors is uncertain. It has
travellers of the world and are
months. All nymphal stages and been suggested that they might
readily transported via luggage,
adults of both sexes require blood play a role in the spread of hepatitis
Serving Westmead Hospital, Western Sydney Area Health Service & Rural NSW
A publication for the Institute of Clinical Pathology & Medical Research

2. Fact Sheet Medical Entomology
B, however, experimental evidence then an approved insecticide, which such as cracks and crevices will
does not support this. has some residual activity, should discourage repeat infestations. As
be applied to all harbourages. bed bugs are cryptic in their habits,
Note that an irritation or bite complete control is often difficult to
experienced in bed may not The synthetic pyrethroids are often achieve with the first treatment.
necessarily be due to a bed bug the main chemicals used for control This is especially so with heavy
infestation. in Australia, however these are not infestations and thus a post control
very effective and can even repel treatment evaluation is always
Laboratory Diagnosis the bugs. The carbamates and the advisable.
A bed bug infestation can be organophosphates are far more
diagnosed by the identification of effective for control, but may not be Confirmation and Enquiries
specimens collected from the recommended for use on Identification of bed bugs, and
infected residence. Collection of live mattresses (check the label). other medically important insects, is
or dead bed bugs, cast skins, performed through the Medical
hatched or unhatched eggs will Non-chemical approaches to control Entomology Department at ICPMR,
determine an infestation. There are involve the use of hot air and/or Westmead Hospital. The Medical
two species of bed bug that wrapping up infested materials in Entomology Department is the only
bloodfeed on humans but Cimex black plastic and placing the articles NATA accredited laboratory in
lectularius has the most widespread in the sun, thereby killing the bed Australia for the identification of
international distribution; the other bugs with the heat generated. arthropods of medical importance.
species, C. hemipterus, is usually However this should only be used
confined to tropical regions. for small items, if at all. Clothes can More Information?
be washed in hot water and dried Please Contact:
Treatment and Control on the hot cycle of the clothes drier. Department of Medical Entomology
If bed bugs are suspected then a Delicate materials can be placed Level 3, ICPMR, Westmead
licensed pest controller should be into the freezer. Generally, Hospital, WESTMEAD NSW 2145
consulted. A careful inspection must pesticides will need to be applied in www.medent.usyd.edu.au
be undertaken and all possible conjunction with any non-chemical www.arbovirus.health.nsw.gov.au
hiding places within infested and means of control. Good
adjoining rooms examined. Once all housekeeping practices and a
likely sources have been identified, reduction in possible harbourages
Lifecycle of the Common Bed Bug, Cimex lectularius
Serving Westmead Hospital, Western Sydney Area Health Service & Rural NSW
A publication for the Institute of Clinical Pathology & Medical Research