Agriculture Reference
In-Depth Information
in the absence of food (Reinhardt and Siva-
Jothy, 2007).
Identifi cation
Identifi cation of the live stages of bed bug
can be made by comparison with Fig. 2.1.
Adults are broadly similar in size and shape
to an apple seed, whereas nymphs vary in
size considerably; fi rst instars (the smallest)
being approximately the size of a grain of
brown sugar.
Like all true bugs (Order: Hemiptera),
bed bugs possess a proboscis through which
they feed. This structure functions like a
drinking straw and is clearly visible pro-
truding downwards from the front of the
head. Anther notable feature is the absence
of wings, which are present in the adults of
most other true bugs.
Unfed bed bugs are dorsoventrally
fl attened but swell during feeding. This
also corresponds to a change in colour,
from chestnut brown to dark red or almost
black in adults, and from pale yellow-
brown to bright red in nymphs, as the
colour of the blood shows through their
thin cuticle.
Bed bugs closely resemble a number of
other species from the same family
(Cimicidae) that are occasionally associated
with human hosts. These include several
species of bat bug, swallow bug, martin bug
and also the tropical bed bug. These bed
bug relatives are not as ubiquitous as the
common bed bug so local knowledge can be
helpful in determining which species are
likely to be encountered. Usinger (1966) has
described the biological keys and other
notes on the identifi cation of the species
within the Cimicidae.
Fig. 2.1.
The life cycle of the bed bug. A single
blood feed is required to progress between each
of the fi ve nymphal instars and from 5th instar to
adult. This occurs at approximately weekly
intervals at normal room temperature.
A single blood feed from a vertebrate
host is required to progress from one instar
to the next. This occurs at approximately
weekly intervals under warm conditions
with unrestricted access to food. However,
development time is highly infl uenced by
temperature and food availability. At 18°C
the life cycle (egg to adult) can take more
than 4 months (Johnson, 1942). At tem-
peratures below 13°C development ceases
entirely (Jones, 1930; Mellanby, 1935). In
the host's absence bed bugs have been
known to survive for more than a year
without food (Bacot, 1914).
Adult bed bugs copulate shortly after
reaching maturity and females begin laying
eggs within about 1 week. Like develop-
ment time, egg-laying rate is a function of
temperature and food availability. At a
temperature of 23°C, and with 1-2 feeds per
week, a female can be expected to lay 6-12
eggs per week (Johnson, 1941). For females
to sustain continuous, fertile egg production,
they must copulate approximately every
5-6 weeks, although natural mating rates
are believed to be much higher (Stutt and
Siva-Jothy, 2001). They must also feed
frequently as egg production ceases rapidly
Behaviour (feeding, harbourage seeking,
dispersal)
Bed bugs are frequently considered to be
nocturnal; however, they readily adapt to
the behaviour of their host and will infest
anywhere that is regularly occupied for
prolonged periods. This includes sofas and
Search WWH ::
Custom Search