We have a very large pile of very old firewood in our yard. I’d like to use it up in the fireplace this winter but I noticed that there seem to be a lot of big black ants moving around in the pile. I figure they’re probably nesting in the wood so I’d like to spray it with pesticide before I bring it inside. Can you recommend a good product?

A. C., Fitchburg, MA

We never suggest that someone spray pesticide on wood that is later going to be burned in a living space. In fact, you won’t find any pesticides that allow that use on the label. That means it would be illegal for you to use the product on firewood.

Don’t Spray Pesticide on That Infested Firewood Because:

• It’s just too risky for your family’s health since burning treated wood could release toxic fumes into an enclosed space.

• Spraying pesticide on the exterior of infested wood probably would not reach and kill any pests that are nesting inside the wood anyway.

• If you have carpenter ants nesting throughout your firewood, it is probably too rotted to be of much use as quality firewood. Carpenter ants usually infest wood that is softened and damp so your wood may be too damp to even burn well (see Carpenter Ants From Firewood).

You should plan on getting rid of that old and infested firewood. But you don’t have to just dump it. Build or buy an outside fire pit, get a bag of marshmallows and a few long, pointed sticks…and have a bonfire!

Plan Ahead to Insure Useable Firewood

In the future, take better care of stored firewood by doing the following:

1. Split the wood as soon as possible. The quicker it dries, the less likely it will become infested by ants or wood-boring beetles.

2. Stack firewood up off of the ground and not directly against the house. Stack it in loose piles to dry more quickly.

3. Store firewood under cover to keep it dry but leave an air space between wood and the cover.

4. Rotate the woodpile. Don’t let a log remain on the bottom of the pile for more than a year.

5. Burn it before it rots. Burn older wood first. Try not to carry over large amounts of wood from season to season.

For more information, see Colonial blog, Keeping Firewood Pests Outside.