ANR-825 CONTROLLING WOOD-BORING BEETLES IN HOUSES
ANR-825, New Jan 1994. Eric P.
Benson, Extension Entomologist,
Entomology, Auburn University.
Controlling Wood-Boring Beetles in Houses
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After termites, wood-boring beetles are the most
important wood-destroying insects in homes. The amount of damage
that wood-boring beetles cause depends on many factors. The type
of wood (hardwood or softwood), the moisture of the wood, and
the environmental conditions at the infestation site all affect
the severity of beetle damage. This publication discusses the
identification and control of some of the most common wood-boring
beetles found in Alabama homes.
Lyctid Powderpost Beetles
Description. In the United States, there are more than
thirty-five kinds of lyctid beetles. These are considered the
"true" powderpost beetles. Generally, adult lyctid beetles
are 1/8 to 1/4 inch long. They are
slender and range in color from reddish-brown to black. Their
heads are obvious when these insects are viewed from above.
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Powdery
wood dust from powderpost beetles often collects in piles in
crawl spaces. |
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Sometimes
powderpost beetle damage creates lines of wood dust on infested
lumber. |
Habits. Lyctid beetles infest only hardwoods, such as
oak. They can live in wood with a wide moisture range, from a
dry 8 percent to a very moist 32 percent.
Only the larvae damage wood. The female lays an average of
twenty to fifty eggs in crevices or on the ends of boards. When
they hatch, the tiny larvae bore down into the wood. As the larvae
grow, they bore to a point just underneath the surface of the
wood, where they change into adults.
After they change, the adults cut a 1/32- to 1/16-inch
circular exit hole in the surface of the wood. Often, powdery
wood dust created by the beetle's feeding is pushed out as the
adult emerges. This is why they are called "powderpost"
beetles.
Males and females exit at the same time and mate, and the new
generation of females lay eggs again. The entire life cycle for
most lyctid beetles takes 9 to 12 months.
Anobiid Powderpost Beetles
Description. There are more than 200 kinds of anobiid
beetles, of which very few infest wood. Most anobiid beetles found
in homes, like drugstore beetles, infest grain products. The few
that do infest wood are also called powderpost beetles or deathwatch
beetles.
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True
powderpost beetles are only 1/8 to 1/4 inch in length and range
in color from reddish-brown to black. Photo courtesy Van Waters
& Rogers, Inc. |
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True
powderpost beetles can damage hardwood furniture such as this
walnut drawer. |
The wood-infesting anobiids range from 1/8 to 1/4
inch in length. Their color ranges from reddish brown to nearly
black. The body segment just behind the head is hoodlike and completely
covers the head when the insect is viewed from above.
Habits. Anobiids can infest both hardwoods and softwoods.
Only the larvae feed on wood. They generally prefer wood in cool
locations with moisture levels above 14 percent. Anobiids are
the most common beetles infesting crawl spaces and outbuildings.
Female anobiid beetles usually lay fewer than fifty eggs under
wood splinters, in cracks, or in old exit holes. Like lyctid beetles,
the small anobiid larvae bore into the wood, where they eat and
develop.
When the larvae change into adults, they chew round exit holes
between 1/16 and
1/8 inch in diameter.
The male and female emerge together and mate, and the female deposits
her eggs. Though the females fly well and can lay eggs at new
locations, they are most likely to lay their eggs on the board
from which they emerged. Most anobiid beetles take 2 to 3 years
to complete their development.
Bostrichid Powderpost Beetles
Description. Bostrichid beetles are sometimes referred
to as "false" or "large" powderpost beetles,
bamboo borers, or even lead-cable borers. The adults range in
color from reddish brown to black. They range in size from 1/8 to 1/4 inch. Like anobiid beetles, the segment just
behind the head conceals the head from above. The heads of most
bostrichid beetles are directed strongly downward.
Habits. Generally, bostrichid beetles cause much less
damage in homes than lyctid or anobiid beetles. Most bostrichid
beetles bore into freshly cut hardwoods, but a few will attack
softwoods. Unlike lyctid or anobiid beetles, both adults and larvae
of the bostrichid beetle damage wood.
Adult females bore "egg tunnels" into wood to deposit
their eggs. After hatching, the larvae tunnel into the wood to
feed and grow. Under most conditions, the larvae complete their
development by the spring of the year following egg-laying. Adults
cut 3/32- to 9/32-inch, round exit
holes when they emerge. The adults rarely reinfest the wood from
which they emerge.
Old House Borers
Description. The old house borer belongs to a group
called cerambycid beetles, which are also known as long-horned
beetles. Most long-horned beetles are wood borers in the larval
stage, but only the old house borer is a serious pest in homes.
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Anobiid
or deathwatch beetles can infest hardwoods or softwoods. Photo
courtesy Van Waters & Rogers, Inc. |
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The
heads of most bostrichid beetles are bent downward. Photo
courtesy Van Waters & Rogers, Inc. |
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![](Images/fig7.jpg) |
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The old house borer is one of
the largest wood-infesting beetles. These beetles cut 1/4 to
3/8 inch oval holes when they emerge. Photo courtesy Van Waters
& Rogers, Inc. |
Adult old house borers range from 5/8 to 1 inch in length. They are brownish black
in color, with many gray hairs on the head and forepart of the
body. The segment just behind the head has a shiny raised bump
on each side, giving it the appearance of a face.
Habits. Old house borers infest softwoods, especially
pine. They can be found in old houses, as their name suggests,
but they are actually more common in new homes.
The females lay about fifty eggs in cracks and crevices in
wood. The larvae penetrate the wood to feed, but they often stay
near the surface. Larvae usually require 2 to 3 years to develop
in wood with 15 to 25 percent moisture, but they can take as long
as 15 years to develop in very dry wood.
Usually, larvae become adults in the spring, but they may not
emerge immediately. When they do exit, the adults cut oval holes
about 1/4 to 3/8 inch in diameter.
Adults are normally most active in June and July.
Control
There are several factors you should consider before starting
control measures for wood-boring beetles. The first is that no
control may be necessary. Many homes have some damage from wood-boring
beetles. However, in many cases the damage is very minor and old,
which means that all the beetles have died. Unless you see beetles
or fresh wood powder around the holes, chemical treatment is not
necessary. Fresh wood powder is usually light in color and does
not clump. Old wood powder is often yellowed and clumps together.
Also, there are many beetles in nature that attack wood but
do not cause serious damage or reinfest lumber in homes. It is
important to know which beetles you have before you go to the
trouble and expense of some of the treatments.
Finally, with the advent of central air conditioning and heating,
the potential for widespread damage has decreased. In fact, even
with the more serious lyctid and anobiid beetles, if a house has
no moisture problems, has a central cooling and heating system,
and is not unoccupied for long periods, serious problems are not
likely.
Spot Treatments. For active wood-boring beetle infestations,
several spot treatments are possible. These include controlling
wood moisture, using surface covers, mechanical removal, freezing,
and insecticide treatments.
Moisture problems are most commonly found in the lumber in
crawl spaces. A crawl space should be well ventilated and, in
many cases, should have a vapor barrier. Generally, plastic sheets
(4 mil polyethylene) covering 70 percent of the crawl space will
keep the lumber from getting too moist. Surface cover, including
paint, polyurethane, and water sealants, will protect wood from
moisture problems and help prevent wood-boring beetles from penetrating
the wood.
However, surface treatments usually do not prevent beetles
already in wood from emerging. If an infestation is limited to
a few pieces of lumber, or if the lumber can be removed easily,
replacing the wood may be the best control strategy.
Freezing temperatures can kill wood-boring beetles, especially
in small furniture. If you have access to a large or walk-in freezer,
you might want to consider this control method. Wood subjected
to freezing should first be tightly wrapped in plastic. Freeze
the item for about a week. After removing it from the freezer,
leave the item wrapped until it reaches room temperature. This
protects the wood from water marks due to condensation as the
item warms. Also, handle the item carefully since glue joints
are very fragile when frozen.
Most insecticides for wood-boring beetles are restricted and
can be used only by certified pest control operators. You may
be able to find some formulations of Dursban (chlorpyrifos) that
are labeled for wood-boring beetles around the home. Most labels
will recommend mixing Dursban in water to make a 0.25- to 0.5-percent
solution. For treatment, the emulsion can be sprayed or brushed
on small areas to the point just before the solution begins to
run off. Before applying the insecticide, remove any surface covering,
such as paint, so the insecticide can penetrate the wood.
As with any insecticide, you must follow the specific instructions
on the label of the product you buy. Since pest control operators
have access to a wider range of insecticides and equipment, your
best option may be to employ a professional.
Fumigation. In situations where spot treatments have
failed or in serious infestations where there are large numbers
of beetles throughout the house, fumigation may be the best control
option. The penetration of fumigants can kill wood-boring beetles
in all areas of the home. However, fumigants cannot prevent future
wood-boring beetle infestations.
Fumigation is expensive and complicated. Fumigation in Alabama
can be done only by an Alabama certified pest control operator.
Before employing a professional, get quotes from several reputable
firms.
Information on the types of wood-boring beetles found in homes
and the damage they cause is summarized in the table below.
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Photographs so designated were taken by Laurence
A. Allen of Van Waters & Rogers, Inc., and were used with
permission.
Use pesticides only according to the directions
on the label. Follow all directions, precautions, and restrictions
that are listed. Do not use pesticides on plants that are not
listed on the label.
The pesticide rates in this publication are
recommended only if they are registered with the Environmental
Protection Agency or the Alabama Department of Agriculture and
Industries. If a registration is changed or cancelled, the rate
listed here is no longer recommended. Before you apply any pesticide,
check with your county Extension agent for the latest information.
Trade names are used only to give specific
information. The Alabama Cooperative Extension Service does not
endorse or guarantee any product and does not recommend one product
instead of another that might be similar.
For more information, contact your county Extension
office. Look in your telephone directory under your county's name
to find the number.
For more information, contact your county Extension office. Visit http://www.aces.edu/counties or look in your telephone directory under your county's name to find contact information.
Issued in furtherance of Cooperative Extension work in agriculture and
home economics, Acts of May 8 and June 30, 1914, and other related
acts, in cooperation with the U.S. Department of Agriculture. The Alabama
Cooperative Extension System (Alabama A&M University and Auburn
University) offers educational programs, materials, and equal
opportunity employment to all people without regard to race, color,
national origin, religion, sex, age, veteran status, or disability.
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