DNR | Do you know what’s in your wood this Firewood Month?

“Wood borer” is a general term for beetles that lay eggs on or in the bark of trees. When eggs hatch, these insects spend their larval stages tunneling into and feeding on wood, destroying tissues that move sap and water through the tree.

Many wood borers are native and seek out weakened trees. Others, such as invasive emerald ash borer and the Asian longhorned beetle (found in nearby states), infest healthy trees and cause their decline and death.

Wood borer eggs and larvae can remain in wood after trees die. Because they often are under bark or within the wood itself, they can go unnoticed until they emerge as adults. A Michigan study of 1,045 firewood pieces transported by the public indicated 23% contained live borers and an additional 41% showed evidence of previous borer infestation.

Adelgids are small, soft-bodied insects that feed on coniferous plants like pines or firs using piercing/sucking mouthparts. Agencies and partners in Michigan’s Invasive Species Program are working hard to prevent the spread of hemlock woolly adelgid in west Michigan. The Michigan Department of Agriculture and Rural Development is managing balsam woolly adelgid in areas of Clare, Missaukee and Oceana counties.

Adelgids are hard to see with the naked eye and are usually detected by the small, white, cottony tufts they spin to protect their eggs. Over time, hemlock and balsam woolly adelgids can kill their host trees by depleting sap and preventing its circulation.

For many Michiganders, spongy moths (formerly gypsy moths) and their munching caterpillars are all too familiar. While female moths can’t fly, they easily spread across the state by depositing egg masses on vehicles, outdoor equipment and firewood, which are then moved around by people.

With invasive spotted lanternfly now present in areas of southeast Michigan, the same scenario is likely to play out again unless we all take the time to look for and remove egg masses from belongings and adopt safe firewood practices.

• Aged or seasoned wood is not safe to move. Just because it is dry doesn’t mean it’s clean. A recent study showed insects continued to emerge from firewood even three years after it had been cut.
• Buy firewood near where you will burn it – a good rule of thumb is only using wood that was cut within 50 miles of where you’ll have your fire.
• Certified, heat-treated firewood is safe to move long distances. Look for a federal stamp or seal on the package, and keep the firewood in the original packaging if entering a campground that requires heat-treated wood.
• If you buy firewood and don’t burn it all, don’t bring it home or to your next destination.
• Tell your friends not to bring wood with them – everyone needs to know they should not move firewood.