Michigan
State University Extension
Home Maintenance And Repair - 01500546
06/24/03
Powder Post Beetles
Powder
post beetles include several small, brownish, dry
wood-eating insects ranging in size from one-twelfth to one-fifth inch
long. Three families, Lyctidae, Anobiidae, and Bostrichidae, are most
common in Michigan.
Powder post beetles were so named because the wood upon which they feed
is generally eaten into a fine, flourlike powder. The Lyctus types feed
primarily on hardwoods; the Anobiids prefer to attack softwoods, such
as conifers. They can damage and, in some cases, eventually destroy (by
completely tunneling) all exposed wood in houses, including furniture
and paneling. Severe damage may take many years to materialize. A case
of this kind usually results from failure to apply early remedies.
Watch for "shot holes" in the wood.
The Lyctus powder post beetles are usually brought into buildings in
lumber which has been stored in yards or at building sites. They may
also be present in furniture, wood paneling, and firewood. Damage is
usually to the starch-rich sapwood of large-pored hardwoods such as
ash, hickory, oak, walnut and cherry. The hardwood floors of new homes
are commonly attacked.
You can easily recognize the work of powder post beetles. When the
adults emerge, usually in June, some species leave small holes about
the size of a pin in the surface of the wood; others make holes the
size of pencil lead. From these holes, a fine, powderlike brood of
larvae carry on their destructive feeding. Normally, these insects have
a 1-year life cycle; this means that the adults will appear only once
each year. And because of this habit the larvae have a feeding period
of many months.
Integrated Powder Post Beetle Management
The sooner these insects are controlled, the better. Delay only makes
the damage greater. But, regardless of how urgent the problem seems to
be, understand what you are doing before going ahead with powder-post
beetle control.
Use chlorpyrifos 42% EC in the spring and summer. Spray infested
unfinished wood. Follow label directions to time spray with beetle
emergence, glue a piece of white paper over damaged area of wood. Begin
treatment when tiny holes caused by the beetles emerging from the wood
appear in the paper. Repeat treatment 3 times at 3 week intervals.
The use of an insecticide emulsion may remove wax from finished floors.
Simply rewax following the drying of the chemical. Do not walk on the
treated floor for several hours, or until it is thoroughly dry. Note: See the Section on warning
for safe use of insecticides in homes.
Paint or varnish all furniture and wood surfaces. This will not stop
the damage done by the grubs already in the wood, but it will
discourage adult egg laying for any other brood. This method is not a
good solution to powder-post damage, unless the adult emergency holes
are kept covered with paint or varnish. Lyctus-type powder- post
beetles normally do not reinfest filled wood.
Fumigation may be advisable in cases of severe powder-post beetle
damage, especially where other methods have failed or where rapid
elimination of the insects is desired. Furthermore, fumigation has
advantages where it is hard to apply other treatments, especially in
cramped crawlspaces or other space-limited areas. However, remember
that fumigation for powder-post beetles or any other insect should be
done only by an experienced, certified pest control operator. Also
fumigation does not prevent reinfestation of wood if it is exposed
afterward to adult powder-post beetles. Fumigants are highly poisonous,
and people can be easily killed by them unless proper precautions are
taken.
For a complete listing of suggested control options for all home, yard
and garden insect pests contact your local Extension Service, found
under local government.
Read and follow instructions on the pesticide label. Heed all warnings.
Check with your physician if you have any concerns regarding your
personal health risk.
References
Revised by Tom Ellis, M.S., Department of Entomology
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