Why are there bugs in my firewood?

JACKSONVILLE, Ill. — With the arrival of winter-like weather, many of us will be firing up the fireplace. When bringing wood inside for the fire, we can sometimes bring some unexpected hitchhikers. Many insects and other critters will use firewood (or wood in general) as a food source or a place to overwinter. Fortunately, for the most part, they pose little to no threat to us or our homes.

Wood-boring beetles

Various beetles will inhabit and feed on wood. While we may see the adults emerging from firewood brought indoors, they aren’t feeding on it; the larvae are.

Longhorned beetles get their names from their long antenna, which can be longer than their bodies in some species. The adults typically range in length from 1/4 to 2 inches long. They are probably the most common wood-boring beetles found in firewood.

Metallic woodboring beetles are flattened and often bullet-shaped. Unlike long-horned beetles, they have short legs and antennae and are often, as the name implies, metallic in color.

Both of these groups of insects will lay their eggs in dying, freshly cut, or recently killed trees, so frequently, the eggs are already in the wood when cut. In many species, the larvae will spend a year or more tunneling and feeding in wood before emerging as adults.

Carpenter ants and termites

Carpenter ants are large (3/8 inch) black ants. While they don’t feed on wood, they will build their nests in wood. Carpenter ants will build their nests in damp, rotting wood. Firewood that has been on the ground for an extended time or has not dried out may become inhabited by carpenter ants.

Termites will nest in the ground but may tunnel into and feed on firewood that has been stacked on the ground. Termites that are found in firewood are workers, which look similar to ants but are whiteish.

Other critters in firewood

A variety of other insects and ‘critters’ may be found in or on firewood, often using it as a place to over winter. Things like spiders, cockroaches, pillbugs (roly-polies), wasps, and ants can occasionally be found emerging from firewood once it’s been inside for a few days.

What should I do about insects that emerge from firewood?

Insects inhabiting firewood will often emerge once they have been exposed to warm temperatures for an extended period. Fortunately, the wood in our homes and furniture is too dry for them to live in, so they do not pose a threat to them. If you do find an insect or something else emerging from your firewood, they can be collected and placed outdoors.

There are several steps you can take to reduce the number of insects getting into your firewood:

Stack firewood off of the ground. This will make it more difficult for insects like termites to get into the wood. It will also allow the wood to dry faster, making it a less hospitable place for insects to develop.

Bring firewood indoors only as needed. Try to bring only a day or two worth of wood inside at a time. The longer the wood is inside, the greater the likelihood that anything inhabiting it will warm up and emerge.

Do not apply pesticides to firewood. The pesticides will not affect any insects that have bored into the wood. Additionally, harmful fumes could be produced when they are burned.