Hitchin’ a Ride: A Review of Firewood as a Vector of Forest Pests in North America
By David Coyle, Ph.D.
The list of devastating forest pests in North America contains some ridiculously impactful invasive species, some of which are capable of wiping out entire tree genera (e.g., the emerald ash borer can kill all species of Fraxinus, or ash species), entire plant families (e.g., the redbay ambrosia beetle impacts all species in the family Lauraceae, which includes avocado and sassafras trees), or all different kinds of tree species (e.g., the Asian longhorned beetle feeds on trees in at least 12 different genera, including maples, willows, and poplars). These forest pests cause millions (if not billions) of dollars in damage and countless ecological impacts, some of which we don’t even know yet. While all can spread on their own, humans are unfortunately one of the main ways they get around.
Speaking of humans, many of us like a fire. Some folks enjoy the occasional fire in the outside fire pit, sometimes allowing their kids to gorge on hot dogs and eat unlimited s’mores. (Don’t judge me; it’s been a long pandemic year.) Others rely on firewood to heat their homes. Growing up in Minnesota, I can remember stacking firewood every year to help get us through the winter. What I didn’t know then—but do know now—is that many pests can survive in firewood, some for more than three years. To that end, there has been a good bit of research on firewood pests, starting in the early 2000s, when the emerald ash borer was really increasing its range in North America. Since then, there have been several studies, but no one has thoroughly reviewed what is out there, what we know, and what we need to know—until now. Our new paper published this month in the Journal of Economic Entomology does just that. Led by Angelica Solano, an M.S. student, with Shari Rodriguez, Ph.D., and me, our team reviewed the firewood pest literature from North America to see what we did and didn’t know, and found some very eye-opening things.
Did you know that most of the work on pests in firewood has been done in the Great Lakes Region? A handful of studies have been done in the southwestern U.S. and in Canada, but almost none in the Pacific Northwest or southeastern states. This is significant because there are plenty of wood-using pests in these areas too, and we have very little idea of what’s happening here. And before I get the “you don’t need a fire in the Southeast because it’s so hot” emails, there are a lot of folks who use it for recreational purposes and heating their home during the winter (it does get chilly in the mountains). In fact, lots of gas stations along the main interstates sell firewood because it’s so commonly brought to campgrounds by weekend campers.
We also don’t have a lot of knowledge on how pest dispersal is affected by movement in firewood. We know many pests can be moved, or can survive in cut wood, but how does human-mediated movement really affect pest population levels or spread? Likewise, we don’t know a lot about what people know (or don’t know) regarding this issue—it’s basically the old Donald Rumsfeld saying, that we don’t know what we don’t know. To more effectively educate people and manage these issues, we need to know how and what people are doing and why. And, unfortunately, there’s a big knowledge gap here.
At the end of the day, we know pests can be moved in firewood. Certainly, which pests are moved will differ based on the location and type of wood, but, regardless of where you are, this is a possibility. We also know that people’s attitudes and knowledge can impact their decisions to move firewood long distances, and that there are inconsistent rules and regulations among states and countries. What would really be beneficial is continent-wide regulations regarding the movement of firewood, enforcement of those policies, and a more informed public. Better to lead with a carrot than to rule with a stick, so a focus on educating the public is, to me, much preferred over new legislation and regulations.
So, if you’re reading this, please—enjoy that fire. Eat those hot dogs and marshmallows. But get your firewood locally.
Journal of Economic Entomology