Use firewood wisely and keep out unwanted pests

Leaving firewood stored indoors can introduce carpenter ants, powderpost beetles and other pests into your home.

What a relaxing feeling in the winter to sit in front of a fireplace while burning logs warm the room. For many of us, living through cold, winter months, a fireplace is essential. Enjoy your fireplace, but take care not to bring unwanted pests into your home. It is always best to bring only the wood indoors that you will use in the fireplace that day.

Many different insects infest dead and dying trees and can even attack freshly cut logs. Insects can feed on wood tissue even after it is cut up into firewood or they may use the wood as a place to build a nest. Insects like the emerald ash borer and the elm bark beetle feed just under the bark, leaving winding trails across the surface of the wood. Others insects, such as powderpost beetles, bore right into the wood, leaving behind small exit holes from their tunnels. Most of the insects that live within firewood are of little concern, but two may cause trouble if they are brought into a home: powderpost beetles and carpenter ants.

Carpenter ants are found in wood even though they do not feed on it. They excavate areas in wood to create places to build their nests and are commonly found in rotting wood. Bringing them indoors can give them access to new sites in which to nest and feed. If you see these large, black ants on your firewood, inspect it for rotting wood that may hold eggs as well as adult ants. Keeping firewood dry and off the ground helps prevent wood from rotting and attracting these ants. Indoors, carpenter ants feed on sweet materials such as honey, sugars and jellies. They range in size from 3/8 to 1/2 inch for workers, while the queen can be 1 inch in length. Carpenter ants brought into a home may search out a suitable site in which to build a nest within the building.

Powderpost beetle damage
Damage from powderpost beetles. Photo credit: Gyorgy Csoka, Hungary Forest Research Institute,

Another pest that may be found in logs is the powderpost beetle. These small beetles lay their eggs on or below the surface of unfinished wood. The young larvae that hatch burrow into the wood, creating small tunnels as they feed on the wood. Often the only sign of these beetles are numerous small pinhole openings in the wood and fine sawdust that accumulates in and around holes where larvae are feeding. Powderpost beetles that come into the home in firewood can move from the logs to other wood that is unfinished, such as frames inside of furniture as well as structural wood within the house. If you find numerous small, pin-size holes in wood and fresh sawdust nearby, it would be prudent to have the beetles identified through the Michigan State University Diagnostic Lab to determine the best course of action in managing this pest.

The take-home message is to store firewood outdoors in an area where it is off the ground and dry. This may mean covering the wood with a tarp or storing it at a site that is protected by the overhang of a roof. Do not pile wood up against the house and do not store it in the garage. Bring in only enough wood to use that day in your fireplace.

For more information on powderpost beetles, visit the University of Kentucky Cooperative Extension Service’s website on Powderpost Beetles. For more information on carpenter ants, visit the University of Minnesota Extension’s website on Carpenter Ants.

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