A variety of creatures live in or on trees cut for firewood or settle in stacked wood that is destined for the stove or fireplace. Loose bark provides a protective winter hiding space for some, while others live in galleries or tunnels in the wood. The residents can warmup enough to become active after their shelters are brought indoors. These stirred-up inhabitants can provide some temporary excitement but do not pose long-term problems.
Many insects attack stressed or dead trees. Their activities ensure that the resources in the wood are broken down and recycled. Beetle larvae are commonly found in firewood (Figure 1).
These include roundheaded borers (Figure 2), flatheaded borers, and shothole borers (also called powderpost beetles). Piles of sawdust appear as the larvae continue to tunnel and feed. The potential for them to infest structural wood in the house is very low. Some species only attack certain tree species, most select wood within a narrow moisture content, others require bark to be present. Sometimes adults emerge after logs are brought indoors. Roundheaded wood borers are brightly marked, fast beetles with long antennae. Many mimic wasps in behavior and appearance (Figures 3 to 5).
Many arthropods hide under loose bark or in cavities during winter. Possibilities include beetles, wood cockroaches, and even overwintering wasp or hornet queens. Spiders and their egg sacks, praying mantid egg masses, and moth cocoons are part of the “life” that may be associated with trees or fallen logs. These creatures will become active after warming up indoors. They can be swatted and discarded as they appear. These insects are not able to survive for extended periods indoors and they will not multiply or become established in homes.
Insect invasion of homes from firewood can be reduced by following these rules:
- Inspect wood as you pick it up. Check surfaces that were on the ground or against other pieces.
- Brush off the creatures that you see and knock wood together to dislodge what you do not see.
- Bring in small supplies that will be burned in a few days, rather than large amounts that could stay in place for weeks.
- In the case of outdoor woodpiles, avoid stacking wood directly on the ground, especially right beside the foundation. This will keep wood from getting too wet and reduce the chances for infestation by termites and ants.
- Never treat firewood with insecticides.
By Lee Townsend, Extension Entomologist