Powderpost beetles are often brought into homes inside some sort of wood material, including building materials, wood furniture, or firewood. The presence of powderpost beetles is often first revealed by small, unexpected piles of powder near wood surfaces or materials and/or small holes (called exit holes) in the wood. If you are noticing piles of a fine powder, this could definitely be cause for concern.
The name powderpost beetle is actually a general label used for a wide variety of wood-boring beetles, including true powderpost beetles (Lyctinae), false powderpost beetles (Bostrichidae), and deathwatch beetles (Anobiidae). While the term powderpost comes from the powder (aka frass) these insects leave behind, it is actually their larvae that cause the most damage. These larvae, also known as woodworms, voraciously eat through wood from the inside, creating tunnels (or galleries) inside the wood. As adults, they chew out of the wood and emerge through small round exit holes.
What Are Exit Holes?
Exit holes are the holes that adult powderpost beetles create when they chew their way out of wood. These holes are not very large. Imagine pounding a small nail into a piece of wood and then removing it: The hole that is left behind would look very similar to a powderpost beetle exit hole.
While there are a number of similarities and differences between types of powderpost beetles, all of them invade and damage wood items, which can include different plants and items including trees, structural wood, bamboo furniture, and decorative wooden items. (Bamboo is technically a grass, but it is also susceptible to powderpost beetle infestation.)
If you suspect there could be powderpost beetles in your home, it is important to address these concerns quickly. More often than not, the activity you're seeing is nothing to worry about, but on the off-chance that you're dealing with wood-boring beetles, the issue will be less severe the faster you address it.
What Do Powderpost Beetles Look Like?
These adult beetles are small (1/16 to 1/4 inch) and vary in coloring in shades of brown and red. True powderpost beetles produce an extra fine, smooth, flour-like powder called frass and leave exit holes that tend to be all the same size. They have a slightly elongated, flattened shape, and if viewed from above, you can often see their head and eyes.
What Is Frass?
Frass is the powdery mix of wood debris and droppings that wood-destroying insects leave behind as they eat the starches in wood. Powderpost beetles create frass, but so do other pests, including termites.
2 Ways to Get Rid of Powderpost Beetles
Remove Infested Wood
If you are certain you have an active wood-boring beetle issue, it is always ideal to remove, destroy, and replace any infested wood, especially when structural wood is involved. Always check wood around the infested wood for holes, as well. Infested wood can be burned or taken to a dump. When replacing the wood, don't forget to inspect building materials (and any free firewood) before bringing it indoors.
Try a Temperature Treatment
Both hot and cold temperatures will kill off powderpost beetles. Wooden items that are small and do not have any fabric, felt, or fur attached can be heated for six hours in an oven at 120°F to 140°F. Items can also be frozen in a deep freezer for a minimum of three days at 0°F. If the item is more than two inches thick, it could take longer than three days to adequately freeze treat wood-boring beetles.
Signs of Powderpost Beetle Activity
Powderpost beetles either start as eggs inside the pores of wood or burrow into the wood to lay eggs. This can make early detection incredibly difficult, as you can't actually see inside the wood where the activity is taking place. Some of the first clues of a powderpost beetle infestation are small and unexpected piles of frass piling up around wood items, as well as exit holes in the wood.
Spotting holes in the wood inside your home or on your furniture doesn't necessarily mean that you have powderpost beetles, though, and it doesn't mean that you have an active infestation, especially if the holes you are seeing are in wood that is sealed, varnished, or stained. It could be powderpost beetles, and it could be an active issue, but it could also be old and inactive. The first and most important step in dealing with a wood-destroying pest is determining what pest is responsible for the damage or activity you're noticing. This will help determine what treatment is required, so work to identify the specific cause of the signs you're seeing as soon as possible.
What Causes Powderpost Beetles?
While the cause of powderpost beetles really depends on what type of powderpost beetle you're dealing with, the short answer is that the beetles wanted to lay their eggs in the pores of something wooden.
How to Prevent Powderpost Beetles
Prevention is the best strategy for keeping powderpost beetles away, as wood-boring beetles are difficult to detect and challenging to manage once an active infestation is established. Sanitation is key in preventing a powderpost beetle issue.
If you are purchasing lumber or other goods made of wood and you're worried about powderpost beetles, try to ensure that there are protective measures that take place during each stage of wood processing and handling. These measures can include:
- Kiln-drying lumber (this only kills off active pests and does not prevent re-infestation)
- Removal and destruction of dead trees and tree limbs, especially near stored wood products
- Special lighting around warehouses and wood storage areas designed to discourage pests
If you can, seal the wood in your home with varnish or paint. This seals the pores and cracks where beetles could lay eggs and can protect your home from powderpost beetles and other wood-destroying organisms.
Powderpost Beetles vs. False Powderpost Beetles vs. Deathwatch Beetles
The label powderpost beetles can actually refer to true powderpost beetles, false powderpost beetles, or deathwatch beetles. All are wood-boring beetles, and they all look relatively similar to one another.
True Powderpost Beetles (Lyctinae)
You will find true powderpost beetles in hardwoods, including hickory, ash, oak, walnut, and mahogany. They are most commonly found in some of the following wood materials:
- door and window framing
Though bamboo is actually a grass, it has large pores that are ideal for adult female beetles to lay their eggs. Female true powderpost beetles emerge and lay their eggs on untreated wood surfaces or cracks. They deposit their eggs in the pores of wood where they will be protected. The true powderpost beetle's life cycle can last between three months to more than one year, depending on environmental conditions.
False Powderpost Beetles (Bostrichidae)
Most adult false powderpost beetles are small and range in size from 1/8 to 1/4 inch, but some species found in the wild can be up to two inches long. Their coloring is dark, ranging from brown to black, and some have reddish body parts, such as antennae, legs, and mouthparts. Their lifecycle varies, with most species maturing in about one year. Some species, however, can take up to 20 years to fully develop.
False powderpost beetles produce the grittiest and most coarse frass of the three groups of powderpost beetles, with the texture feeling similar to soap flakes. You will see it in the exit hole, but it will be difficult to dislodge due to its texture. False powderpost beetle exit holes are all about the same size. Infestations of these beetles happen in both hard and soft woods, though they are more commonly found in hard woods.
Some species of Bostrichidae beetles come from imported tropical woods such as bamboo, certain types of mahogany, and some firewood. Some species are also found in dying walnut and oak tree branches and ornamental hardwood trees, such as eucalyptus.
Adult female false powderpost beetle behavior differs from that of other powderpost beetles. They burrow into the wood instead of laying eggs on the surface or looking for cracks. After creating tunnels (also called egg galleries), they will find a pore or crack inside the wood to deposit their eggs into. Due to this behavior, they will also burrow into other materials if it means laying their eggs in a safe place. This is how they have earned alternative names such as the leadcable borer or cask borer.
False powderpost beetles are capable of burrowing into wood and non-wood materials that include plaster, soft metals such as lead and silver, metal coated electrical/telephone cables, and wine-soaked oak barrels and corks
Deathwatch Beetles (Anobiidae)
Though their name is a little strange, these beetles are actually related to various stored-pantry pests, including the cigarette beetle and the drugstore beetle. Deathwatch beetles typically range in size from 1/4 to 3/8 inch and are a reddish to dark brown color. Just like Lyctinae beetles, they lay their eggs in the pores on the surface of wood or in exposed, cracked wood as opposed to burrowing into the wood first. Their life cycle can take up to two years to complete.
Deathwatch beetle frass consists of very small pellets that are more coarse than true powderpost beetle frass, but not as coarse as frass from false powderpost beetles. Exit holes from deathwatch beetles are unique, as they can be various sizes, unlike the other two powderpost beetle families. Deathwatch beetles primarily infest soft woods, their favorite being Douglas fir. Douglas fir is often used in support beams (ceiling, foundation, etc.) and furniture.
Wood that is old or decaying is ideal for deathwatch beetles, as they prefer moist wood and are found more commonly in damp environments.
Identification of Powderpost Beetles
If you are noticing powderpost beetle activity, there are a few tests you can use to try and determine what insect might be causing the issue. You can also try simple observation: While this method isn't fool-proof, you may be able to tell precisely what kind of beetle infestation you have by looking at the beetles' backs. True powderpost beetles can have a more elongated appearance. If you look down on their back from above, you can see their head and eyes. False powderpost beetles and deathwatch beetles both have a hump-backed appearance. If you look down on their backs from above, you cannot see their head and eyes easily.
If you cannot tell what type of beetle you have based on looking at them, try the ballpoint pen test or the frass test.
You may want to wear a mask or respirator and gloves if you are coming into contact with frass. While frass is generally harmless to humans, there have been cases where people have had allergic reactions after handling it, including respiratory and skin irritations.
The Ballpoint Pen Test
Insert the tip of a ball point pen into the exit holes you see. Compare the holes to the descriptions below to try to determine what type of creature may be making them.
True Powderpost Beetle: The holes are all about the same size and the exit hole is small, so only the very tip of the pen fits.
False Powderpost Beetle: The exit holes are all about the same size and the entire point of the pen fits into the exit hole.
Deathwatch Beetle: The holes vary in size and fit both the tip of the pen as well as the angled part of the top of the pen.
Drywood Termite: Some of the holes are filled with mud, which can camouflage them and make them difficult to see at all.
The Frass Test
Examine the frass closely, using a pen tip or other tool if necessary to dislodge some from the exit holes. Compare the appearance, texture, and consistency of the frass to the below to try to determine what might be causing the holes.
True Powderpost Beetle: Smooth and fine frass, similar to the texture of flour
False Powderpost Beetle: Frass is incredibly gritty and difficult to dislodge from exit hole
Deathwatch Beetle: Gritty, coarse frass that feels like soap flakes
Drywood Termite: Large, granular pellets with ridges on the sides, similar in texture to ground pepper
Where do powderpost beetles come from?
Powderpost beetles come from wood (or bamboo) materials that haven't been properly treated or protected against potential infestation. They are commonly brought into homes via building materials, wood furniture, or firewood.
Will powderpost beetles go away on their own?
If powderpost beetles are able to find plenty of wood surfaces on which to lay their eggs and otherwise have a welcoming environment where they're able to find enough sustenance and shelter, they likely will not leave unless forced to.
Do powderpost beetles bite?
Powderpost beetles are unlikely to bite humans or pets, though they can cause damage to homes, furniture, and other wood items.
How long do powderpost beetles live?
True powderpost beetles will live from three months to more than one year, depending on how conducive the environment is to their survival. Other types of beetles commonly referred to as powderpost beetles (false powderpost beetles and deathwatch beetles) can live anywhere between two and 20 years.
When to Call a Pro
In severe cases or when removal and heat treatment are not possible, chemical treatment will likely be necessary. Be sure to shop around and find an Integrated Pest Management Specialist if you need professional pest help. There are very effective and safe professional quality products containing sodium borate that will kill wood-boring beetles and protect wood in your home from a variety of wood destroying pests for years to come.
There are videos on the internet that encourage homeowners to attempt sodium borate treatments themselves, but sodium borate products should always be applied by a licensed professional. Improper treatments can cause environmental and health risks, as well as damage to your property.
“Powderpost Beetles.” Penn State Extension
"Bora-Care: The Green Solution to Wood-Destroying Organisms." Nisus Corporation.
"Work-Related Allergies in Insect-Raising Facilities." Morbidity and Mortality Weekly Report, Centers for Disease Control and Prevention, 1984.