Bed Bug Management - Urban Insect Pests: Sustainable Management Strategies - page 13

Faecal spotting

bugs. A positive indication by a bed bug
canine should always be backed up by
visual inspection and never taken as the
sole justifi cation for applying a treatment.
The use of bed bug canines is a specialist
skill. Dogs need regular training and
handlers must understand the subtleties of
their own dog's behaviour, including its
strengths and weaknesses. If live bed bugs
are hidden inside containers during training
exercises, it is essential that identical,
empty containers are also hidden to ensure
that the dog is targeting the scent of the bed
bugs rather than the container they are
secreted in.

Shortly after feeding and for approximately
2 weeks thereafter (Naylor, unpublished
data), bed bugs defecate aqueous faecal
droplets, ranging in colour from cream
through to black. On bed sheets these
droplets are readily wicked into the fi bres,
resembling a spot of ink. When deposited
on un-absorbent surfaces such as varnished
wood, they dry to form a raised spot usually
1-2 mm in diameter (see Fig. 2.2c,d).
Similar faecal spots can be produced by
fl ies, spiders and even cockroaches, so it is
important to take note of the location.
Spots high up on the walls, on windows or
on the ceiling are less likely to be from bed
bugs. Forensic blood detection kits have
recently shown promise in distinguishing
the faecal spots of blood-feeding insects
from those of non-blood-feeding insects.
At least one kit is now marketed specifi cally
for this use.

Electronic noses

Electronic sniffi ng devices are also available
to assist pest control technicians in the hunt
for bed bugs. These devices detect a range of
gases and volatile chemicals that are
associated with bed bugs. Historically,
electronic sniffi ng devices have never come
close to the sensitivity of canines, but this
technology is improving all the time. The
latest devices, based on portable gas
chromatography-mass spectrometry (GC-
MS) machines, have shown promise in
laboratory trials, and may soon be available
to buy, albeit at signifi cant cost.
All inspections, whether carried out by
humans, dogs or machines, should focus on
the key harbourage sites but it should be
noted that bed bugs have the potential to
hide anywhere in a room, particularly if
they are disturbed either physically or by
the use of insecticides. Key sites to focus on
include:

Cast skins
As part of a bed bug's development through
the nymphal stages, the outer layer of its
body is shed multiple times, allowing it to
grow. These 'cast skins' can be a helpful
indicator of an infestation. They are fragile,
pale yellow-brown structures, 1-5 mm in
length. With experience, cast skins of bed
bugs can be confi dently distinguished from
those of other insects (see Fig. 2.2a,d).

Canines

The use of canines for bed bug detection is a
rapidly growing industry. Canines have
exceptional powers of scent detection and
are particularly useful in screening large
areas or numbers of rooms in situations
where time is limited. Studies have identi-
fi ed variability in the accuracy of scent
detection teams at identifying infestations
(Wang and Cooper, 2011). It is therefore
important to remember that bed bug canines
are a tool for aiding in the detection of bed

• anywhere inside divan (box-frame) beds;
• around the headboard;
• between the two halves of a split bed
base;
• between the edge of the mattress and the
bed base;
• around the ends of the wooden slats of a
bed frame; and
• any furniture in close proximity to the
bed.