Powder Post Beetles
Three species of powder post beetles are of importance since they have shown they will re-infest a structure under the right conditions. They are the Lytcid, the Bostrichid, and the Anobiid.
Lyctid Powder Post Beetles
True Powder Post Beetles are small, from 1/8 inch to 1/4 inch and are reddish brown to black. Unlike Anobiid and Bostrichid Powder Post Beetles, the head of the Lyctid Beetle is visible from above. These beetles have an 11 segmented antenna, which ends in a too segmented club.
The presence of small piles of very fine flour-like wood powder or frass, on or under the wood is the most obvious sign of an infestation. Even a slight jarring of the wood makes the frass sift from the holes. There are no pellets or large bits of wood. The tiny exit holes are round and vary from 1/32 of an inch to 1/16 of an inch in diameter.
Infestations of Lyctids are often introduced into structures in hardwood cabinets, furniture and molding that is made from infested lumber. Lyctids attack the softwood or sapwood of hardwoods with large pores, for example: oak, hickory, ash, walnut, pecan, poplar, wild cherry, and many tropical hardwoods. Bamboo can also be infested. The size of the wood’s pores is important because the female lays her eggs in the pores. Usually, only newer wood is infested because the larvae eat the starch in the wood. As the wood ages, it's starch content decreases. Because softwoods have smaller pores and low starch content, they are not often infested. Eggs are never laid in varnished, painted, waxed or finished wood.
Bostricid Powder Post Beetles
Most Bostricid Beetles are very small, being 1/8 of an inch in length and from reddish brown to black in color. The typical Bostricid body is long and cylindrical in shape. The wing covers have rows of deep pits and some species have spines or jagged margins on their rear end tips. The antennae are short, with the last three or four segments enlarged and saw-toothed. Bostrictid Beetles have their head positioned below their prothorax where it is hidden from above.
Bostricid Beetles usually bore into wood to lay their eggs, so the first sign of an infestation is a circular entry hole from the egg tunnels by the females. The exit holes made by adults are similar, but are usually filled with frass. The frass is meal-like and contains no pellets. It is tightly packed into the tunnels and does not sift out of the wood easily. The exit holes are round and vary from 3/32 of an inch to 9/32 of an inch in diameter. If damage is extreme, the sapwood may be completely consumed.
Bostricid Beetle infestations are generally found in new hardwoods, although softwoods may be attacked. Bostricids rarely cause significant damage in framing lumber and primarily affect individual pieces of hardwood flooring or trim. Only rarely will they attack and re-infest seasoned wood. Just because exit holes are found, does not mean that an infestation is active. The regular appearance of frass after it has been cleaned up is usually a sign of live activity.
Anobiid Powder Post Beetles
Small brown beetles ranging from 1/16 to 5/16 of an inch in length. The body shape is variable, ranging from long and thin to broadly oval. The head of this group of beetles is not visible from above. Two other Anobiids that infest stored products and could be confused with the wood damaging species are the Cigarette Beetle and the Drugstore Beetle.
The frass of most adult Anobiid Beetles contains numerous fecal pellets which are often stuck together in clumps. This is very different from the frass of Lyctid or Bostricid Beetles. The most obvious sign of an infestation is the accumulation of powdery frass and tiny pellets underneath infested woods or streaming from exit holes. If there are a large number of holes and the powder is bright and light colored like freshly sawed wood, the infestation is both old and active. Anobiid tunnels are normally loosely packed with frass and pellets.
These are important wood destroying beetles. Anobiid Beetles attack both hardwoods and softwoods, however, the wood they attack is generally old and not new wood. They will re-infest seasoned wood if environmental conditions are favorable. Attacks often start in poorly heated or ventilated crawl spaces and spread to other parts of the house. The control measures used for Powder Post Beetles depends on what type of wood item is infested, where the infestation is located, and the extent of the infestation.