Enjoy Firewood, but Insects May Emerge

Above banner image from Purdue Extension publication E-67-W

For many homeowners, firewood is a popular source of fuel for winter heating, and in my humble opinion, hard to beat on a cold winter day. Although most firewood pests pose no direct threat to the home, its contents, or its occupants, a Purdue Extension specialist wrote that they can become annoying when they emerge inside the home.

Timothy J. Gibb, Purdue Extension entomologist, authored a Purdue Extension publication entitled, “Insects in Firewood,” publication number E-67-W. Below are some highlights and insights from Gibb’s work.

Wood-boring beetles that may be present in firewood include long-horned beetles (also called round-headed borers), flatheaded borers, bark beetles and ambrosia beetles. These insects may emerge from firewood if stored indoors too long before burning. However, these insects do not attack finished, seasoned or dried wood inside the home.

Firewood stacked outside on the ground for a long period of time, or not allowed to dry out sufficiently, can be subject to attack by carpenter ants. These large black or reddish ants may be up to 3/8-inch-long. Bringing carpenter ant infested wood into the home generally will not spread the infestation inside the home. Only wood that is higher than normal in moisture content is susceptible to carpenter ant damage.

Gibb said that wood stacked on the ground can become infested with termites. Their presence is not usually noticed until the wood is moved during the summer or fall. Infested wood may have mud tunnels on the outside, or tunnels may be noticed if the wood is split. Termites may appear dormant during the winter months in these areas. Firewood should not be treated with insecticides. Termites accidently brought indoors with firewood will not infest structural wood. However, their presence in firewood piled close to the home may warrant a home inspection for termites.

Many spiders, small beetles, wood roaches, sowbugs, pillbugs, wasps, ants and small flies may hide and/or overwinter in firewood. These pests generally leave the wood within a few days after being brought indoors. Most of them are harmless.

Homeowners must accept that nuisance insects will be brought into the home with firewood. After being warmed up they become active and may become nuisance pests. Recognizing these pests and knowing where they are coming from may reduce your anxiety when they are discovered.

Gibb said that homeowners should not make a practice of applying chemicals to firewood for pest control because of the possibility of harmful fumes being produced when the wood is burned.

He said the following guidelines may be helpful in reducing firewood pests:

1. Cut wood in mid- to late fall. This may make the wood less attractive to attack by borers that emerge in the spring.
2. Bring firewood indoors only as needed, at most a couple of days supply at a time. Storing firewood in the home for long periods speeds insect development inside the wood, which allows them to emerge inside the home.
3. Do not stack wood up against the house or garage. This can result in moisture or insect problems in the building. A minimum of 3 feet between the firewood and building should be maintained. This also allows better air circulation, which promotes more rapid and thorough drying of the wood. Stacking the wood off the ground whenever possible also will increase drying and reduce potential pest problems.

For additional information, search for Gibb’s publication, “Insects in Firewood,” at Purdue’s Education Store at: www.edustore.purdue.edu.