Powderpost Beetle

Summary: Powderpost beetles are the most damaging insect homes after termites. The wood boring powderpost beetle doesn't do as much long-term damage as termites, but infestations can be very difficult to treat.

First, the good news. Powderpost beetles cannot destroy a home overnight. Now, the bad news. Powderpost beetle infestations are actually more common than you might think. Their damage often is blamed on other wood boring insects like termites.

The powderpost beetle bores into wood to lay its eggs, and once the eggs hatch the larvae feed on the wood below the surface. They do not emerge until they are adults capable of flight. With their damage often being below the surface, Powderpost beetles can spend a year or two below the surface, and sometimes, when they inhabit very dry wood, they can remain below the surface for over ten years.

The most recognizable sign of a powderpost beetle infestation is the emergence of the adult beetles. The beetle is dark brown or black, about a quarter of an inch long. Their head is visible in some species, but hidden beneath their shell in other species. The other obvious sign of their presence is the discovery of very fine powdery substance on the floor near or beneath a piece of furniture. That material, of course, is the frass or insect excrement which contains fine wood particles.

The important thing to know about Powderpost beetles is that they damage houses very slowly. Their appearance is not cause for panic, and they rarely infest houses to the extent that they cause structural damage. The most common way that Powderpost beetles get inside the wood in homes is when the wood is being stored and dried before it is used for construction. The Powderpost beetle does not commonly infest wood in houses that is more than five years old, unless there is moisture damage present. Powderpost beetles also rarely attack wood that is sanded down, pressure treated, kiln dried, or coated in pain or varnish. They also avoid very dry wood, so wood in homes that are temperature regulated with air conditioning and heat systems are less prone to attack.

It is relatively easy to prevent future Powderpost beetle infestations, but rather difficult to get rid of a current infestation. One way to tell if an infestation is old or current is to look at the frass that is coming out of the Powderpost beetle exit holes. When the beetles exit the wood they leave a hole about a 1/16th to 1/8th of an inch wide. The sawdust-like powder falls from the holes as they exit, and the powder can continue to come out of the hole for a long time because it gets knocked out by vibrations. New frass is light colored and fine to the touch. Old frass has yellowed and clumps together. Knowing that an infestation is no longer present can save you a lot of time trying to get rid of something that isn't there.

Damage to wood

When powderpost beetles emerge they usually fly to another location, but will occasionally try to lay eggs in old exit holes. Plug up exit holes with wood putty or plaster of Paris to prevent this. You can also use varnish, paint, or a surface insecticide treatment to prevent further infestation. Insecticidal surface treatments will not kill larvae below the surface but will prevent reinfestation. Commonly, borates like Bora-Care, Shell-Guard, Guardian, and Tim-bor are used as surface treatments.

For a serious infestation of Powderpost beetles you might have to call a pest control professional. Fumigation might be necessary to reach Powderpost beetle larvae while they are still below the surface. Fumigation of furniture can be expensive and can be done only by licensed professionals. In most cases it is not required as Powderpost beetle infestations will run their course and measures can be taken to prevent reinfestation.