Powder Post Beetles

Powder Post Beetles


People rarely see powder post beetles. The adult beetles range from 2-5 mm long and are reddish brown. Their eggs are 0.5 mm long, white, and teardrop shaped. Their larvae are white, C-shaped, and 5-6 mm long when they are fully developed. Pupation takes place just beneath the surface of the wood. Heavily-infested wood becomes riddled with holes that are packed with frass – wood that has passed through the digestive tract of the powder post beetles.


Wood-infesting beetles cause extensive damage to buildings, especially in coastal areas of Washington State. The damage is often overlooked, as these insects live in portions of the structure that people can’t easily see.

The breakdown of wood caused by a beetle infestation can lead to serious structural weakness. Chemical treatments and wood replacements to curb insect damage are costly. Hemicoelus gibbicollis (LeConte), a member of the beetle family Anobiidae, causes the most significant damage.

Several other anobiid species reside in wooden timbers, but they do not cause serious problems. Infestations usually build to damaging levels over a number of years.

Structure-infesting anobiids reside primarily in older homes that have crawl spaces or damp basements. These beetles also infest outbuildings, such as barns or garages. Wooden support timbers, floor joists, and sub-flooring are commonly infested. The insects will attack new and old hardwoods (maple, walnut, oak) and softwoods (Douglas-fir, cedar, hemlock.) Larvae also feed on plywood.

New replacement wood attached to old, infested wood is more likely to be attacked and show damage very quickly. The new wood has higher nutritional value that attracts the insects. The beetles will continuously reinfest the wooden structure until only powdery frass (feces) covered by a thin layer of wood remains. Conditions of high moisture, no ventilation, and poor drainage away from the structure encourage development of these insects. Homes in Washington west of the Cascade Mountains are most susceptible because beetles favor structures near coastal areas.


Treatment starts with a thorough inspection from one of our licensed pest control professionals with a wood destroying organism endorsement issued by the state. They’ll look for the primary source of the infestation and any other areas that are attracting the beetles. Afterwards, recommendations are given for changes that can be made by the property owners to further repel the beetles. Then, a pesticide application may be performed if necessary.

Chuck Sullivan Exterminators uses Borate products and materials to treat areas of infestations. These materials are usually applied to the flooring, joists, beams and sill plate areas of the sub-structure of the building.