BAT BUGS
Susan
C. Jones, Ph.D., Assistant
Professor of Entomology,
Extension Specialist,
Household & Structural
Pests and Kyle K. Jordan,
Ph.D., Research Associate
1991 Kenny Road, Columbus,
OH 43210-1000
Bat
bugs are bloodsucking
insects. They are free-living
parasites (ectoparasites)
of bats, but they will
bite humans in the absence
of their normal hosts.
In Ohio, most of the
specimens from homes
are bat bugs (Cimex
adjunctus) rather than
bed bugs (Cimex lectularius).
However, in the past
decade, bed bugs have
begun making a comeback
across the U.S. and
have been increasingly
reported in Ohio, although
they are not considered
to be a major pest.
Information on bed bugs
is 
provided in OSU Fact
Sheet HYG-2105-04. Related
cimicids, swallow and
swift bugs, are encountered infrequently (see OSU
Fact Sheet HYG-2105B-04).
Distribution
The family Cimicidae
has a world-wide distribution.
Identification
All members of the family
Cimicidae are small,
oval-shaped, and extremely
flattened if they have
not fed recently. After
feeding, their body
appears plump and dark-colored
from the blood meal.
All have small, stubby,
non-functional wing
pads. They have piercing-sucking
mouthparts that appear
beak-like.
It is important to be
able to differentiate
bat bugs from other
cimicids because effective
control relies on eliminating
the appropriate host.
Bat bugs and bed bugs
are practically indistinguishable
to the naked eye, even
to a trained entomologist.
Microscopic examination
is needed to tell them
apart. Adults of both
are about ¼ to
3/8 inch long and reddish-brown.
The wing pads of the
bat bug are broader
than those of the bed
bug. Another distinction
is that the fringe hairs
on the pronotum (the
upper covering of the
thorax) of the bat bug
are as long or longer
than the width of the
eye, but are shorter
in the bed bug.
Life
Cycle
Bat bugs may survive
for a year or two without
a meal, but blood feeding
is required by the female
in order to produce
eggs. The females lay
eggs on rough surfaces
and in cracks, usually
in the same areas where
the bugs hide. Eggs
hatch in one to two
weeks, and nymphs can
feed immediately. Nymphs
must acquire a blood
meal in order to molt.
Younger nymphs are practically
colorless unless they
have fed, in which case
the blood meal creates
a highly visible dark
spot in their digestive
tract. The exoskeleton
becomes darker as the
bug matures. Adults
can live for a year or more.
Development from egg
to adult averages 1.5
months, but developmental
rates vary depending
on food availability
and environmental factors.
Development from egg
to adult may take from
2 weeks in warm, favorable
conditions to more than
15 weeks in less favorable
conditions. Multiple
generations may occur
within a year since
bat bugs can continue
to breed throughout
the season in the warmth
of a structure.
Habits
Bat bugs feed on all
of the common bats in
Ohio, but they are most
frequently associated
with the big and little
brown bats, which roost
in colonies. Although
bats are their primary
host, these bugs also
may feed on alternative
hosts including humans,
birds, and rodents.
Bat bugs hide in dark,
protected sites and
they prefer tight, narrow
retreats. Bat bugs typically
are found in cracks
and 
crevices in bat
roosting areas, rather
than on the hosts themselves,
but they make repeated
visits to the host to
obtain a blood meal.
Home
Invasion
The main means of dispersal
for bat bugs is phoresy
(hitching a ride on
a bat to a new location).
Bat bugs enter homes
by clinging to the fur
of their host animal.
Typically, bat bug infestations
originate from bat populations
established in attics,
wall voids, unused chimneys,
or uninhabited portions
of the house. Bat bugs
typically do not wander
far from occupied bat
roosting sites where
they have easy access
to food. However, if
their normal hosts are
eliminated or vacate
the area, they will
seek other sources of
food and may crawl about
and invade living areas
within the house.
Bat bug infestations
in living areas usually
occur in cracks and
crevices in the mattress
and bedding, but can
spread to gaps in woodwork,
trim, and furniture,
or behind peeling wallpaper.
These bugs sometimes
crawl up walls to hide
in pictures, frames,
wall hangings, and drapery
pleats.
Feeding
Behavior
Bat bugs typically feed
while the host is sleeping.
The bug pierces the
skin with its extended
mouthparts then injects
saliva as it feeds on
blood. Immature bugs
can acquire a blood
meal in a few minutes,
whereas an adult will
feed for 10 to 15 minutes.
They then crawl to a
hiding place to digest
their meal. When they
are hungry, bugs will
again travel to find
a host.
Injury
to Humans
Humans may not feel
the bite of a bat bug,
though their bite is
reportedly more painful
than that of a bed bug.
Many people develop
an allergic reaction
to proteins in the injected
saliva from the bug.
Humans experience varying
degrees of immunological
reactions to bug bites,
but a welt or lump at
the site of the bug
bite and severe itching
are the most common
reactions. Bug bites
cause a colorless welt
that may become inflamed;
in contrast, mosquito-
and flea-bites have
dark red centers. Often,
a series of two to three
welts occur in close
proximity to each other. Scratching the welts may cause them to become
infected. Discomfort
from bug bites may last
a week or more. Bat
bugs apparently are
not natural vectors
of human pathogens.
Control
Measures
Legal
Considerations -- Bats are non-game
wildlife and therefore
legally cannot be killed.
Specific questions should
be directed to the local
department of wildlife
or a pest management
company.
Integrated
Pest Management--Control
of bat bugs can be complicated
because it relies on
the control of both
the bugs and their regular
hosts. If the host bats
are not eliminated,
bugs are likely to reappear.
Simply spraying to kill
the bat bugs may provide
a temporary solution
but is unlikely to eliminate
the problem. Control
is best achieved by
following an integrated
pest management (IPM)
approach that involves
multiple tactics, such
as preventative measures,
sanitation, and chemicals
applied to targeted
sites. Severe bat bug
infestations are usually
best handled by a licensed
pest management professional.
Prevention--Weatherproofing
the home will prevent
roosting by bats and
therefore prevent the
occurrence of bat bugs.
Caulk cracks and crevices
in the building’s exterior
and repair or screen
openings to exclude
bats and also to exclude
alternative hosts such
as rodents and birds.
Pay particular attention
to bat entry points
Bats most commonly enter
a building at the roof-wall
joint, under loose fascia
boards, unscreened or
broken attic vents,
and other cracks resulting
from building deterioration.
Host
Removal and Exclusion--Bats
and other hosts should
be removed and excluded
from the home to more
permanently remove the
sources of bat bugs.
Coordinate this first
step with insecticide
treatment of harborage
areas, because an increased
movement of bugs into
the living area may
occur after host removal.
If bat bugs are a problem,
it is necessary to exclude
bats from roosting in
the building. Exclude
bats during the late
fall after they have
left the building. DO
NOT attempt to exclude
bats between late April
and mid-August when
young bats are unable
to leave the roost.
They can become trapped
indoors, die, and create
an odor problem.
Secondary insect pests
also may invade to feed
upon the dead bats.
In order to prevent
trapping bats in the
building, exclusion
effort typically should
take place during September
in Ohio.
Bat exclusion involves
first locating the entrance/exit
holes. This is best
done at dusk as the
bats are leaving to
find food. Sometimes
the holes that bats
use to access structures
may be very small--bats
can squeeze through
an opening about 3/8-inch
wide. Dark, greasy smudge
marks may be evident
on the wall just below
the region where the
bats are entering and
leaving the building.
After entrance/exit
holes have been located,
the remainder of the
house also should be
inspected for cracks
and crevices that could
provide alternative
entry points. Caulk gaps or replace mesh
in vents or hire a contractor
to weatherproof the
house.
After sealing all of
these cracks and crevices
in the house, affix
a piece of mesh fabric
(approximately 1.5-2
feet long) over the
bat entrance/exit holes.
This piece of fabric
should be affixed to
the top and two sides
so that it covers the
holes, but the fabric
should remain free at
the bottom. As the bats
encounter the fabric,
they are able to crawl
down it and exit, but
are unable to navigate
their way back inside.
The holes can be sealed
once you have ensured
that all of the bats
have made their way
out.
Insecticides--At
the same time that host
animals are removed
and excluded from a
structure, it is necessary
to treat their harborage
areas with an insecticide.
Treat the original site
of infestation, typically
bat roosting areas in
attics, unused chimneys,
or uninhabited portions
of the house. A total-release
aerosol “bomb” can be
used, but should not
be the sole insecticide
treatment. Residual
insecticides (usually
pyrethroids) are useful
in attics to control
bat bugs. These insecticidal
treatments also should
be directed at cracks
and crevices that bugs
can use to migrate from
the attic, such as areas
around light fixtures.
Dust formulations are
useful to treat wall
voids and attics. Pest-strips
containing dichlorvos
can be used in attics,
but they should not
be placed in living
areas of the home.
In living areas, control
measures for bat bugs
and bed bugs are similar.
Insecticide treatments
should target sites
where the bugs hide,
such as the mattress,
box springs, and bed
frame, as well as cracks
and crevices in window
frames, door frames,
floors, carpet tack
boards, baseboards,
electrical boxes, furniture,
pictures, and ceiling
moldings. Residual insecticides
(usually pyrethroids)
are applied as spot
treatments to cracks
and crevices. Increased
penetration of the insecticide
into cracks and crevices
can be achieved if accumulated
dirt and debris are
first removed using
a vacuum cleaner. Avoid
using highly repellent
formulations, which
can cause bugs to scatter
to many places. Repeat
insecticide applications
if bugs are present
two weeks after the
initial treatment (it
can be difficult to
find all of the hiding
places and hidden eggs
may have hatched). Most
aerosol pest sprays
(“bombs”) are ineffective
by themselves for controlling
bugs.
No insecticides are
labeled for use on bedding
or linens. These items
should be dry cleaned
or laundered in hot
water and dried using
the ‘hot’ setting. Do
not use any insecticide
on a mattress unless
the product label specifically
mentions such use. Note
that very few insecticides
are so labeled. If using
an appropriately labeled
insecticide on a mattress,
take measures to minimize
human pesticide exposure.
Apply the insecticide
as a light mist to the
entire mattress, opening
seams, tufts, and folds
to allow the chemical
to penetrate into bug
hiding places. Allow
the treated surface
to dry completely before
use. Do not sleep directly
on treated mattress;
be sure bed linens are
in place. Do not treat
mattresses of infants or ill people.
Sanitation--Sanitation
measures include frequently
vacuuming the mattress
and premises, laundering
bedding and clothing
in hot water, and cleaning
and sanitizing dwellings.
After vacuuming, immediately
place the vacuum bag
in a plastic bag, seal
it tightly, and discard
it in a container outdoors
– this prevents captured
bugs from escaping back
into the home. A stiff
brush can be used to
scrub the mattress seams
to dislodge bugs and
eggs. Discarding the
mattress is another
option, although a new
mattress can quickly
become infested if bugs
are still on the premises.
Steam cleaning of the
mattress is not generally
recommended because
it is difficult to get
rid of excess moisture
within the mattress,
which can lead to problems
with mold, mildew, house
dust mites, etc.
After the mattress is
vacuumed or scrubbed,
it can be enclosed in
a zippered mattress
cover such as that used
for house dust mites.
Any bat bugs remaining
on the mattress will
be trapped inside the
cover. Leave the cover
in place for a year
or so since bat bugs
can live for a long
time without a blood
meal.
Locations
Serving the St. Louis Metropolitan area since 1956, including
Arnold, Ballwin, Chesterfield, Crestwood, Creve Coeur, Des Peres,
Fenton, Florissant, Kirkwood, Maryland Heights, Overland, St.
Charles, Webster Groves, Wentzville and surrounding areas.
In Illinois: Belleville, Collinsville, Edwardsville, Columbia,
Madison, Waterloo, O’Fallon, Granite City, Alton, St. Clair, Monroe
and surrounding areas.
Columbia & Jefferson City, MO and surrounding areas.
