Powderpost beetles are actually several different types of small insects, who leave behind a powdery substance while tunneling through the wood. Because of this powderpost beetles can be quite destructive to your home. In fact, only termites cause more damage to dry, unseasoned wood. The amount of damage caused by a powderpost beetle infestation depends on a variety of factors including whether it’s a softwood or hardwood, the moisture content of the wood, plus other environmental conditions.
The three most destructive types of powderpost beetles are the lyctid powderpost, the bostrichid powderpost, and the anobiid powderpost. The lyctid beetle is generally thought of as the “true” powderpost beetle. It only infects hardwoods, meaning infestations are most often found in places like furniture, flooring, and doorframes. The bostrichid powderpost is known as the “false” powderpost. They prefer freshly cut hardwood and are often found in tropical hardwoods, such as bamboo. Both the lyctid and the bostrichid are unlikely to infest structural building components, making them not commonly found in crawl space.
Anobiid powderpost beetles, on the other hand, do pose a threat to the structure of homes and are the most likely species to be found in crawl spaces. They bore into both soft and hardwood, leaving behind a round hole between 1/16 and 1/8 inch in size. Unlike other species of powderpost beetles, anobiid powderpost beetles can digest cellulose in wood for food. This gives them the freedom to not depend on starch or nutrients in wood, which will dissipate with age. Generally, anobiids are most commonly found in southeastern or coastal states, where there is both high humidity and high temperatures.
Source: Anobiid Powderpost beetle
Damage from Powderpost Beetles
There are actually over 200 types of anobiid beetles but only a few bore through wood, and thus are described as anobiid powderpost beetles. The anobiid powderpost is normally 1/8 -1/4 inch in length and ranges in color from reddish brown to dark brown. They prefer cool locations with moist wood that ranges from a 13% to a 30% wood moisture content. A drier wood moisture content makes it impossible for larvae to develop. This makes crawl spaces and basements ideal nesting areas with the majority of living areas not being humid enough.
In the right environment, female anobiids lay larvae in cracks, splinters, or old exit holes of moist wood. The development of the larvae actually creates the tunnels in the wood. As larvae grow, they bore through the wood until they are right below the surface. Once the beetles have matured into adults, they cut an exit hole in the wood. As the beetles emerge, they leave behind a powdery substance. Female anobiid beetles typically lay eggs in the same board from which they emerged.
Although powderpost beetles have the potential to cause severe damage, they often go unnoticed since both tunneling and larvae development happen below the wood surface.
Furthermore, it is rare to see actual beetles since they are active at night. Usually, powderpost beetles are discovered by the exit holes and appearance of powder. Once evidence of beetles is discovered, there are often mistakes in whether it is a current or old infestation. You can tell if the infestation is currently active by the type of powder left behind. If the powder is yellowed, clumped together, or covered in dust, it is most likely an old infestation. On the other hand, if the powder is light in color, and does not clump, it is an active infestation. You can also check the appearance of the exit holes. In an old infestation, the holes will seem weathered.
Once it’s determined to be an active infestation, they’re a couple different treatment options. These range from utilizing freezing temperatures to using insecticides to replacing the infested wood. When it comes to anobiid powderpost beetles, however, you will probably need a treatment designed for a larger area. This could include some sort of fumigation to kill the current infestation, plus controlling the moisture in the affected area.
Moisture control is an important component in preventing future infestations. For instance, in an infected crawl space, you will want to make sure the crawl space is properly sealed plus utilize a dehumidifier. This will allow the crawl space to maintain a suitable moisture level, in addition to keeping the wood moisture content low.
Potter, Michael F. “Powderpost Beetles.” Entomology at University of Kentucky, University of Kentucky College of Agriculture, Food, and Environment, June 2018, entomology.ca.uky.edu/ef616.
Zongoli, Patricia A. “Wood-Boring Beetles in Houses.” Home & Garden Information Center | Clemson University, South Carolina, Clemson Cooperative Extension, 6 Jan. 2001, hgic.clemson.edu/factsheet/controlling-wood-boring-beetles-in-houses/.