Powderpost beetles chew small holes in old wood and fence-posts. They leave behind a fine residue of chewed wood that looks like dry powder. The term ‘powderpost beetles’ actually refers to many different species of beetle. All of these beetle species chew wood or lay eggs where their larvae can chew and tunnel through wood.
Here are three facts to know about powderpost beetles:
You many never see an actual beetle
The most common species of powderpost beetles are the lyctids. Black lyctid beetles measure between 1/16 and 1/4 inch long. Lyctids only infest hardwoods cut from broad leaf trees like oak, ash, hickory, walnut, poplar, and cherry. They will usually not be found in building joists and walls which are made of softer woods. Instead lyctids commonly infest hardwood trim, flooring, and window and door frames.
Lyctids are elusive and rarely seen. They lay their eggs in susceptible wood and they fly away. They mostly move at night and are hard to see even in the daytime. The eggs hatch and the larva chew small tunnels through the invested wood. They emerge as adult beetles from small holes and fly off to infest new hardwoods.
Bostricid beetles are lighter brown and also very small. Unlike lyctids, bostricid beetles bore holes in wood to lay their eggs. You will rarely see powder in a bostricid infestation.
Anobiid powderpost beetles infest both hardwood and softwood. The powder found around their emergence holes often feels more gritty than that of the beetles that infest only hardwood. Unlike lyctids and bostricids, anobiid beetles are attracted to moisture and are often found in humid southern states.
Many people mistake weevils and the brown or black beetles that sometimes infest flour and dry foods for powderpost beetles. Carpet beetles also get misidentified. A good rule of thumb is that if you are only seeing the beetles and no holes or powder around wood, you probably aren’t looking at a powderpost beetle.
Not all infestations are active
Sometimes a new homeowner finds holes and powder in wood trim or door frames and immediately assumes the worst. But powderpost beetles will not usually re-infest the same wood. The adults will fly off to greener pastures once they emerge.
To determine if you have an active infestation or just old wood that was once infested, plug all the holes with petroleum jelly. Clean up the wood powder. Come back in a few days. If you see new holes and more powder, you have an active infestation. If not, relax.
Powderpost beetles holes are often found in antique furniture. Since beetles will not infest wood that has been stained or varnished, nothing has to be done about antique furniture evidence of infestation. It almost certainly is old damage from a time when hardwood was not processed with heat or insecticide to prevent beetle infestations.
However, if you need peace of mind ask the antique dealer for a receipt showing which company performed the fumigation on the antique and when. If the item has never been fumigated, you can have this done by a specialist who will take the piece to a special closed chamber to perform the fumigation. Do not attempt to drench the item in hardware store poisons. Doing so is dangerous and ineffective.
Powderpost beetles can be prevented and managed
Seeing a pile of powder around wood trim in your house can be alarming. The first thing to do is make sure the damage is not being done by termites or carpenter ants. Once you have determined your home is termite-free, check to see if the damage is fresh or old by plugging the holes and checking back in a few days.
If you do indeed have an active infestation you need not panic. Spray the holes with a mixture containing mostly borates.
To prevent further infestations, do not store furniture in sheds or garages. Do not use wood that has not been kiln-dried to 145 F. degrees when you build or remodel. If you live in a humid locale, make sure your home has year round temperature and humidity control.
Powderpost beetles may be alarming but they do not general do extensive damage to a home. Arming yourself with knowledge and confidence is the best approach.