Firewood Pests

Random, sluggish insects wandering inside a home in the dead of winter could be wayward fall invaders that come out of hiding, or they could be escapees from the firewood pile. There are two categories of insect pests associated with firewood: Those that are living inside the wood, often feeding on it, and those that are simply sheltering in the woodpile.

The primary wood-destroying insects living inside the wood are termites and carpenter ants. Both can be found in firewood piles, especially wood that is damp or is stacked directly on the ground. Other tunneling insects include horntail wasps and wood-boring beetles such as round-headed borers, powderpost beetles, bark beetles and ambrosia beetles. Of course, most of these insects are already tunneling in the wood before it is even cut.

PESTS IN THE WOODPILE. A woodpile provides excellent shelter for many insects, especially during cold weather. “Sheltering-only pests” include most occasional invaders or nuisance pests that can be found around a home’s foundation. Most of these are pests that require a high moisture level, such as earwigs, centipedes, millipedes, sowbugs, pillbugs, psocids and springtails. Others such as crickets, scorpions, ground beetles and cockroaches are just enjoying a protected site. You also can find fall-invading insects such as multicolored Asian lady beetles, stink bugs and overwintering wasps. And there can be predators in woodpiles, like the black widow spider (wear heavy gloves when handling firewood).

“WILL THEY INFEST MY HOUSE?” This is a common question when firewood pests end up inside. Most nuisance pests in the sheltering category will not cause any damage indoors and usually die in a short time. The primary concern for homeowners and PMPs is whether termites, carpenter ants or wood borers could infest wood in the home. The answer is almost certainly “no.”

While these wood-infesting insects are capable of infesting wood in a home under certain circumstances (usually when moisture levels are high), the required combination of circumstances almost never occurs. Firewood pests are a temporary nuisance. They rarely survive to become pests indoors because (1) they’re usually brought inside in small numbers; (2) they’re sluggish from their semi-hibernation and can be easily captured; and (3) most have a hard time surviving and reproducing in drier, indoor conditions. Termites and carpenter ants in firewood often are separated from their colony when they end up indoors.

It usually takes a day or two after wood has been brought inside before the hitchhikers warm up and become active. They’re usually sluggish and may head for windows, trying to get back outside.

TREATING FIREWOOD FOR PESTS? You probably get calls about firewood pests in two different situations: a customer realizes that his outdoor firewood pile is full of termites, or insects are seen coming out of firewood that is brought inside for burning.

In the first case, that termite-infested wood is probably wet and of little value in a fireplace. Suggest that your customer have an outdoor bonfire instead to get rid of the wood (and the termites at the same time!). There are no pesticides registered for direct spraying of firewood and any treatment of the wood likely wouldn’t reach the pests tunneling inside anyway.

There are some products that allow treatment of the soil or other surface underneath firewood before it is stacked. Some granular pesticides can be used in and around woodpiles for treatment of carpenter ants.

Never spray wood that is to be burned in a fireplace because of the risk of inhalation of potentially harmful fumes. Random firewood insects found wandering indoors can usually be picked up with a vacuum cleaner. If larger numbers occur, treat them as you would any occasional invader with a pesticide labeled for general control of crawling and flying insects indoors.

FIREWOOD MANAGEMENT. The best control for pests in firewood is to educate your customers on how to properly store, dry and use the wood to eliminate future pest problems. Letting the wood dry quickly and properly before use is the key to eliminating many insects that could later cause problems indoors. Wood that is properly seasoned will be too dry for most wood-boring insects to survive. Advise your customer to:

• Split or saw large pieces to speed drying time.
• Stack firewood in loose piles up off the ground and away from the house.
• Rotate the woodpile — don’t let a log remain on the bottom of the pile for more than a year.
• Bring in only a few pieces at a time for burning.
• Remove the bark from the logs before bringing them inside. This will remove many insects that overwinter under bark.

The authors are well-known industry consultants and co-owners of Pinto & Associates.