There is nothing like a roaring fire to take the chill out of your bones on a cold day, but sometimes when firewood is brought into the house, uninvited guests come in as well. Fortunately, the insects that live in logs or under the bark will not harm you or your home.
Several species of beetles are attracted to stressed or dying trees. Female bark beetles lay eggs just under the bark. When the larvae hatch out, they tunnel between the bark and sapwood as they grow and feed. After the larvae pupate, adult beetles emerge. Depending on the species, there may be more than one generation per year. Bark beetles are quite small, from 1/16 to 1/8 inch in length, and often attack trees in groups, so there may be large numbers of beetles in infected trees.
Long-horned beetles, named for their antennae, are also attracted to freshly cut or dying trees. The large, round-headed larvae may spend one to three years tunneling through the wood before turning into an adult.
Metallic wood-boring beetles, like the emerald ash borer, are usually small but often have a metallic sheen; they are sometimes referred to as jewel beetles. Their life cycle is one to two years.
A number of other insects, such as millipedes and pillbugs, seek refuge from cold winter temperatures under loose bark. To minimize nuisance insects in your house, the best thing to do is simply to bring in wood when you are planning to burn it. Typically, it would take one to two days for any insects to warm up and become active, so plan accordingly.
Ideally, firewood should be stored outdoors and off the ground, to help deter some ground dwelling creatures from seeking refuge in woodpiles. Keeping the logs off the ground also aids in drying the wood. Of course, this will not affect the boring insects that are inside the cut wood. They are most often found in dying and recently deceased trees, but if the wood is allowed to season for six months to two years, depending on the species of tree, most of the beetles will have exited before you burn the wood.
Never store wood on the ground next to your house or other building as you may be providing a home or food for termites or carpenter ants. Termites nest in the ground but could feed on your logs. They create mud tunnels to get from their nest to their food source. If you find that the firewood stacked against your house has a termite infestation, seek a professional pest control operator to examine your house for damage.
Carpenter ants do not feed on wood but they excavate soft, water damaged wood for their home. They come out at night to look for food. Piles of wood stacked on the ground near homes may have some water-damaged logs at the bottom. These could be attractive to carpenter ants. While they might enter your home looking for food, they typically only create nests in areas with water-damaged wood. Piles of sawdust are often a sign that something is amiss.
We occasionally get questions about spraying the firewood with some sort of insecticide. This is not recommended. First, it would be highly unlikely that the insecticide could penetrate into the wood where any boring insects might be. And second, handling or burning wood ladened with pesticides could be a health hazard.
If insect pests do come in with your firewood, don’t be alarmed. Just vacuum or sweep it up and discard it or catch and release.
Once again, the UConn Home & Garden Education Center will be at the Connecticut Flower and Garden Show, Feb. 22 – 25 at the Convention Center in Hartford. Bring a half cup of soil for a free pH test and your garden questions will be answered by our staff and Master Gardener volunteers.
If you need to have an insect identified or have questions on insects found in firewood or other horticultural topics, feel free to contact us at the UConn Home & Garden Education Center, 877- 486-6271; visit our website at www.ladybug.uconn.edu or contact your local Cooperative Extension center.