Powderpost beetles are the most destructive beetle pests of seasoned wood. The other important wood destroying insects are carpenter ants and termites. The common name "powderpost beetle" comes from the habit of reducing sound wood to a very fine powder, often kicked out of small exit holes when the adult beetles emerge.

Adult powderpost beetles are quite small (1/8" - 1/4"), dark brown to black and cylindrical. Most of their life is spent as larvae (grubs) tunneling in wood. When mature adults chew its way out of the wood, leaving behind a small, circular exit hole. Males and females then mate, egg laying occurs on the wood surface where hatching larvae enter the wood to begin the cycle again. The complete life cycle (egg - adult - egg) may be as short as several months or as long as many years. It depends on the species, the nutritional quality of the infested wood and overall temperature and moisture conditions.

One family of powderpost beetles, the anobiids, prefers damp wood, and thus is more common in coastal areas or in situations where wood is allowed to remain damp. Another group prefers seasoned hardwood (like furniture) and may require many years to complete development. Old furniture can suddenly develop exit holes! More commonly, exit holes begin showing up in trim wood around cabinets and along baseboards one to several years after manufacture.

Kiln drying of wood kills all stages of powderpost beetles. However, kiln drying alone will not prevent wood from becoming infested if it is exposed to an active infestation. We are sometimes asked to determine where, or when, a particular piece of wood became infested. Most of the time, this is impossible. Many times, it is even difficult to tell the difference between active and inactive infestations unless live beetles are found. An "inactive infestation" is one in which evidence of beetle attack is present (such as exit holes and tunnels) but no live beetles or larva are found.

You may be tempted to "tent and fumigate" houses with real or suspected powderpost infestations. While it may be effective under certain circumstances, I don't generally recommend fumigation for residential houses. Fumigation is very expensive and provides no long term residual control at all. Infested wood should be removed and replaced; new and existing wood should be treated with a residual insecticide. These residual treatments will prevent new infestation by emerging beetles. In addition, you must solve any existing moisture problems before attempting any other treatment. Finally, I strongly recommend yearly inspections for powderpost beetles, carpenter ants, and termites.

Copyright © 2000 Jack DeAngelis, Oregon State University. All right reserved

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