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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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This information.was reviewed as of June 2008.  For more information about the contents please contact costner@msu.edu for webpage problems strausc@msu.edu .