Preventing and Controlling Powderpost Beetles in and Around the Home J
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PNW 326 • Reprinted July 1995 Preventing and controlling Powderpost beetles in and around the home J. DeAngelis he common name powderpost beetle loosely applies to three closely related beetle families, Lyctidae, Anobiidae, and T Bostrichidae. Powderpost beetles breed in dead wood, as well as dried and cured lumber. It is their larvae’s feeding that reduces wood to what scientists call frass—a fine powder or a mass of small pellets. Damage by powderpost beetles occurs in a wide variety of wood products—floors, molding, paneling, crates, furni- ture, antiques, tool handles, gunstocks, etc. Damage usually is not evident until myrtle, and mahogany. Bamboo is also adults cut holes and emerge; then the subject to attack. powder becomes visible (Figure 1). Adult lyctids (Figure 3) are flattened, Where damage is extreme, wood is slender, dark brown to nearly black 1 converted to a mass of powder or beetles generally 3 to 6 mm long ( ⁄10 to 1 pellets held together by a thin outer ⁄5 inch). Mature larvae are C-shaped surface penetrated by numerous exit and slightly hairy, with three pairs of holes. Damage this severe usually small, spinelike legs immediately indicates that several generations of behind the head. Larval body color is beetles have reinfested the same piece yellowish-white, and the head is tan to of wood (Figure 2). brown (Figure 4). Females mate after emerging from Lyctidae wood and lay most of their eggs the first Lyctids are the true powderpost week. Eggs are deposited within pores beetles. Larval feeding within wood of wood or in cracks and crevices. Upon produces a frass as fine as face powder, hatching, larvae begin feeding on and which will stream from the exit holes tunneling into the wood. After the at the slightest jar or tremor. The larval feeding is complete, pupation appearance of powder does not occurs just below the wood surface. necessarily indicate an active infesta- Adults emerge by chewing a small tion. Remove the wood and examine it circular hole 2 to 3 mm in diameter closely to confirm the presence of live through the remaining wood. The insects. complete life cycle (from egg to adult) You may not see adult beetles; ordinarily requires 9 to 12 months; however, they’re attracted to light and under favorable conditions, it may be may appear on windows or sills. Have reduced to only 6 or 7 months. Under them identified by an expert. There are adverse conditions, the life cycle may be many look-alike beetles such as bark prolonged to 2 to 4 years or longer. beetles from fireplace wood. Lyctids attack only large-pored Revised by Jack D. DeAngelis, Extension hardwoods such as oak, ash, hickory, entomologist, Oregon State University. A Pacific Northwest Extension Publication • Oregon • Idaho • Washington Emergence hole Wood dust Figure 1.—Anobiid powderpost-beetle damage. Figure 2.—Lyctid powderpost-beetle damage. Two lyctid species that are com- give the frass a slightly gritty feel. mon pests in the Pacific Northwest Once the sapwood is consumed, are Lyctus planicollis LeConte and infestations may die out. If there are Lyctus brunneus (Stephens). The latter large numbers of exit holes and frass species frequently is found in furni- is bright and light-colored like freshly ture made from bamboo. sawed wood, the infestation is old and active. Anobiidae In the Pacific Northwest, anobiids Anobiid powderpost beetles attack are most common in unheated or sapwood but only rarely heartwood. infrequently heated buildings. They Figure 3.—Adult lyctid. Unlike the lyctids, anobiids reduce do best in wood with a moisture wood to pellets, instead of a fine content above 14 percent. Coastal powder. second homes, wooden shelters or Adults range from 3 to 7 mm long, buildings in rest areas, bridges, etc. and their slender, cylindrical bodies are all susceptible to attack. generally are reddish-brown to nearly black. In most anobiid species, Bostrichidae the head is bent downwards, and the Bostrichids are most abundant in eyes are not visible when viewed the tropics, so they’re not as impor- from above (Figure 5). The larvae, tant as the lyctids and anobiids in Figure 4.—Lyctid larva. similar to lyctid larvae, are C-shaped temperate regions. However, some and nearly white except for a dark- species do attack wood in the Pacific ened head capsule (Figure 6). Northwest. Most bostrichids feed on The life cycle of anobiids may the sapwood of hardwoods, but a few require 2 to 3 years for completion, also attack conifers. depending on the prevailing tem- Bostrichid adults typically are 3 to perature and condition of the wood. 6 mm long, with slender, cylindrical Adult exit holes are round and range bodies. Their reddish-brown to black from 1.6 to 3 mm in diameter. color is similar to other powderpost An important member of this beetles. The head projects downward family is the native powderpost as in species of anobiids, and the eyes beetle, Hadrobregmus gibbicollis are not visible from above. Figure 5.—Adult anobiid. (LeConte). This beetle is most abun- The segment immediately behind dant along the coast, where it com- the head often bears numerous short monly attacks unpainted Douglas-fir spines that produce a rasplike timber in barns and bridges and the appearance (Figure 7). The larvae are basement timbers of dwellings. also C-shaped grubs; however, in this Greatest damage usually is confined family, the segments immediately to the lower portion of structures. behind the head are much wider than The frass of anobiids is tightly the segments near the tail end packed in the galleries (feeding (Figure 8). areas). It is not powdery but com- An exception to the general appear- Figure 6.—Anobiid larva. posed largely of tiny fecal pellets that ance of adults of this family is the “black polycaon beetle,” Polycaon wood products are stored and manu- stoutii (LeConte). This coal-black factured. bostrichid is 12 to 25 mm long, and Once you discover an infestation, its prominent head extends forward. there are steps to eliminate the The segment immediately behind the infestation and prevent reinfestation head does not have a spiny surface and further damage. Base your (Figure 9). decision to use one or more of the The bostrichid life cycle is similar control measures described below on to that of other powderpost beetles, the value, size, and use of your but its egg-depositing behavior is infested wood. Figure 7.—Adult bostrichid. unique. Female beetles bore into wood and prepare “egg tunnels” Painting or coating the surface instead of laying eggs in pores or Before the female powderpost cracks on the wood surface. beetle lays an egg (or begins egg The frass of bostrichids is meal-like tunneling, as with the bostrichids), and contains no pellets. It is tightly she first “tastes” the wood to deter- packed in the galleries and does not mine whether it contains enough sift out of the wood easily. starch and sugar to nourish her Although they’re found occasion- offspring. If you coat the surface with ally, the bostrichids are not consid- paraffin wax, varnish, shellac, or ered a serious pest of structures in paint, you’ll prevent “tasting,” and Figure 8.—Bostrichid larva. the Pacific Northwest. When prob- eggs will not be laid. lems occur, they originate in hard- Larvae already in the wood at the woods shipped from other more time of coating will continue their susceptible parts of the country or development, but you’ll have mini- from other countries. Many of the mized the possibility of reinfestation species do not infest wood after it has by a new generation of beetles. It’s been seasoned, so damage is limited also recommended that you patch all to that inflicted by the first genera- existing holes before you apply any tion. surface treatment. The black polycaon beetle attacks any softwood and several hard- Freezing woods. It sometimes burrows into You can place small wooden the softwood interior of certain articles, and even infested furniture, Figure 9.—Adult black multiple-ply veneers, and it produces in a home freezer or large walk-in polycaon beetle. damage that may not be noted until freezer to kill existing beetles and adult beetles bore through to the grubs in the wood. To sufficiently surface of panels that have been reduce temperatures within infested made into furniture. wood, keep these articles in the Dinoderus minutus (Farbicius), the freezer (at or below 0°F) for at least bamboo powderpost beetle, is found 48 hours. in baskets, picture frames, furniture, and other bamboo material imported from the Orient. Insecticides and fumigation Some homeowners may wish to Prevention and control employ a professional pesticide applicator to control infestations by Most powderpost beetle infesta- using an insecticide or fumigant. tions are present in wood or wood These treatments may be expensive, products before purchase. Infesta- and you should consider the value of tions are discovered when new adult the infested articles before you begin emergence holes or powdery frass such treatment. form on finished wood products. Therefore, prevention and control should begin at the lumber mill and For further reading continue in lumberyards, builders’ Anobiid Beetles in Structures, EB 1577, lots, and other areas where wood or by Daniel A. Suomi (Washington State University, Pullman, 1991). Figures 1 and 2 were created by Gary Parsons, research assistant in entomology, Oregon State University. This publication was originally published as Extension Circular 1098, by Ben Simko, Extension agent, Malheur County. In 1988, it was revised by Joseph Capizzi, Extension entomologist emeritus, Oregon State University, with the cooperation of Extension specialists in Washington and Idaho. Pacific Northwest Extension publications contain material written and produced for public distribution.