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.