Farming Magazine - July, 2014


Firewood and Invasive Insects

By J.F. Pirro

A tree-lined street in Toledo, Ohio, in 2006, before emerald ash borer infestation.
Photos by Dan Herms, Ohio State University.

Pick your analogy to describe the onslaught of emerald ash borer (EAB) - the No. 1 enemy of forests and firewood these days - and no matter which one explains it best, the pest is still outwitting us at a frightful pace.

Most say it's like fighting a slow-burning forest fire, but it's harder to put out. Like the blight that annihilated the American chestnut tree, EAB is capable of wiping out a genus. Thirty years ago, woodlot owners were battling gypsy moths; today they're waging war against beetles, largely EAB and the Asian long-horned beetle (ALB).

ALB will put holes in a tree. It infests and kills a large range of deciduous trees. EAB does not destroy the heartwood of ash trees, because the larvae remain in the layer between the bark and the heartwood, but it functionally kills virtually all North American ash trees that it infests. The few anecdotal accounts of surviving ash trees, those called "lingering ash," are rare and only interesting from a high-level scientific perspective. To salvage ash, it must be harvested or removed before being attacked by EAB.

In the Northeast, the general effort is about preserving the pristine woods of yesteryear, but for the region's woodlot owners, those woods are the source of their livelihood. "People love trees for the economic value, but also for their beauty," says Leigh Greenwood, manager of Don't Move Firewood, a national outreach and education campaign that addresses the problem of invasive forest pests by concentrating on the root cause - moving firewood.

The same street three years later, in 2009, after the invasive insect

Most of these invasive insects wouldn't disperse themselves within 2 or 3 miles on their own, but when they're transported with firewood, you run the risk of spreading infestation to new areas. "If emerald ash borer was never moved, it would be in one or two states instead of 22," says Greenwood. "It starts in the tree [and] kills it, but then is retained in the wood [that's moved]."

While ash isn't a predominant tree in the Northeast, it's a special tree - it's the primary shade tree used in urban townscapes, it's a source for baseball bats, and lots of animals use its seeds.

On his 360 acres in Everett, Pennsylvania, Dave Schreffler has largely reclaimed his forest by taking out large stands of Virginia pine, leaving the property as a hardwood forest and restoring wetlands for wildlife habitat. He has thinned the woodlot and divided it into managed areas based on topography and soil types. The trees are mainly oak, with some sugar maples and ashes. Since there are ash trees, there will also be EAB, but he's not about to let the bad guy undo all his work.

Schreffler has 50 acres in hay and pastures for meat goats and hair sheep; the rest is woodland. Operating as Greenbrier Enterprises, Schreffler's woodlot business depends on a strategic management plan that includes leasing the land to a second-generation hunting group to minimize the deer population.

Wood from a maple tree severely infested by the Asian long-horned beetle.
Photo by Patricia Douglass, USDA-APHIS PPQ.

At least every other year, he's been able to draw an income from either a timber harvest or from government grants to support various forest improvement plans.

"At first, like others, I just saw it as just being there and I let it go," Schreffler says. "Then I saw it as an opportunity, so I applied for grants to improve it, and then began drawing money off the harvests. I began to see my forest as another crop."

The 72-year-old Schreffler knows that much of what he's worked to restore will take another 80 years to pay someone else back. "I'd like to sell the trees now and have them take my management plan and see it continue - to sell it off like we do with development rights," he says. "These would be tree rights."

When he does harvest, the wood is sourced out to various markets. The pulp goes to paper mills, the hardwood to local dealers, and the veneer to associated buyers at the mills. The treetops become firewood, much of it sold to a sawmill to heat its plant and offices. Some 4-foot lengths are sold as a heat source for a local gym.

This cut maple branch shows deep tunnels and damage from Asian long-horned beetle larvae.
Photo by Patricia Douglass, USDA-APHIS PPQ.

However, it's his work with biological controls that has earned him the most recognition and satisfaction; he combatted gypsy moths that would otherwise defoliate his oak trees, and he used wasps to protect his hemlock trees. Some of his predator insects are imported from Germany.

When it comes to the ash and EAB, which was first detected outside Detroit in 2002 and on Schreffler's property this spring, everyone is still experimenting. Schreffler says a couple of observations are proving true. Larger groves of ash do better than smaller independent sections, though no one is sure why.

EAB is now in 51 of Pennsylvania's 67 counties. However, it hasn't yet been detected in Maine or Vermont.

One reason EAB is more difficult to control is that it takes a year or two before there's overt evidence that ash trees are affected. It can take that long to see the larvae come out of the tree and leave behind a small D-shaped hole. Schreffler says he won't give EAB its one to two years to emerge.

"You start by looking at the life cycle of the insect," he says. "It's not different with alfalfa in the fields. This is just another crop to manage."

Schreffler received a grant that was used to purchase 30 nesting boxes for northern flickers. He puts the boxes about 12 feet high in ash trees. Northern flickers, which love EAB, will nest and help manage the insect.

His research revealed that Oobius agrili, a gnat-sized wasp that parasitizes EAB eggs, could help. Several states are finishing a five-year study of the wasp as a biocontrol. O. agrili was released in Shawnee State Park, which is near Schreffler's woodlot. If the study shows the wasps can reduce EAB, Schreffler will need to find a place to source the predators.

Another wasp, Spathius agrili, is known to attack EAB larvae, but questions remain, such as: What is the optimal ratio in a given area? How many wasps need to be released in a given area to be effective? How often should they be released?

Biocontrols aren't cheap, but Schreffler says he isn't spending as much as he would if he were spraying. Spraying may be quicker, but it's topical, and he says insects get into places that spraying doesn't.

It seems cold weather is another EAB deterrent. He notes that some areas have experienced 80 percent reductions in EAB activity if the region's winter temperatures dip to between 0 and minus 16 degrees Fahrenheit for at least a six or seven-day period.

Any proactive steps are a plus, including education. That includes presentations to bird and nature clubs or to woodlot owners associations.

With help from a grant, Dave Schreffler was able to purchase 30 northern flicker nesting boxes, which he hangs about 12 feet high in ash trees. The box is filled with sawdust/shavings that the woodpeckers pull out to create a nest. He says the species loves the emerald ash borer. Inset, Northern flicker.
Photo courtesy of Dave Schreffler.

"What it really takes is to get people to spend time in their own forests," Schreffler says. "You have to get out and take a look. Look for woodpeckers. If you see woodpeckers, you know you've got it [EAB]."

The state of affairs

In the more immediate realm of prevention, some states in the Northeast, such as Maine, have established bans on out-of-state firewood to help eliminate the threat of EAB, ALB or other invasive pests.

Maine's quarantine took effect in 2010. It forbids bringing firewood into Maine unless it was heat-treated to a core temperature of at least 160 degrees Fahrenheit for 75 minutes. It must be accompanied by a treatment certificate or label from a USDA-qualified facility or similar documentation from an analogous state agency in accordance with the USDA Plant Protection and Quarantine Treatment Manual, or from analogous Canadian authorities.

To sell firewood in Maine, you must prove it came from an in-state source (with a bill of sale, harvest notification report, trip ticket, etc.), or if the firewood came from out of state, you must show that it was accompanied by a treatment certificate or label.

Dave Struble, state entomologist with the Maine Forest Service, says, "Bugs have no respect for borders. They have come from everywhere and nowhere, and they're going everywhere and nowhere. It's like chasing fog, and we're always behind the curve."

EAB in particular has provided what Struble calls a "teachable moment." It has become an eye-opener, and now it's all about messaging.

"We have to change popular behavior," he says. "I'd like to say we're doing a better job in the New England states, but that's not true. The Midwest has been on the edge of it. We have an advantage in that we can study their experience with it and learn before it becomes a problem here. We're at ground zero here, but we're all in this together."

It seems like ALB can be controlled and eradicated, but Struble doesn't believe that will be the case with EAB. "We can prepare people so they can learn to deal with it, but we're just buying time," he says. "It's gotten ahead of us before we've been able to get hold of it. Right now there are no real game-saving tools."

Photo by James Cote/

In New England, ash makes up about 4 to 5 percent of the hardwoods in the states' forests. In Pennsylvania, ash is about 3.7 percent of the forest. Seventy-one percent of Pennsylvania's woodlands and about 95 percent of Maine's are privately owned. There are roughly 730,000 private landowners in Pennsylvania, so it's not easy to get the word out to everyone while managing a consistent approach. Donald A. Eggen, forest health manager with the Pennsylvania Department of Conservation and Natural Resources, says it's a daunting task.

Pennsylvania has already developed management plan templates for communities and parks to deal with EAB, Eggen says. Plans are to use components of the state forest plan for private forest landowners. The worst plan is to do nothing. "You can't wait until you see woodpecker damage," Eggen adds.

State agencies worked in cooperation with USDA agencies to form the Pennsylvania Forest Pest Task Force. The task force initially prepared response plans to deal with EAB, ALB and thousand cankers disease, but is now busy drafting an overall response plan for any new forest invasive species.

"The word is out," Eggen says. "The number of calls is up. We've trained the forest service. We're talking to woodlot associations. We're taking state management plans and then tweaking them for private landowners, but there are still a lot of absentee landowners."

The national movement

Since all the states have reacted differently, and no two state quarantines seem the same, the national Don't Move Firewood campaign is significant. For the last five years, the campaign has been funded primarily by the USDA's Animal and Plant Health Inspection Service. When it launched in 2008, the USDA Forest Service Northeastern Area provided seed money in cooperation with The Nature Conservancy. Don't Move Firewood partners with hundreds of state agencies and nonprofits in all 50 states and Canada, including the Society of American Foresters, the American Firewood Producers and Distributors Association, the Forest Service and others.

"A lot of people realized that something needed to be done, but everyone was banging their own drum," Greenwood explains. "No one was putting it all together."

Using its partnership model, educational outreach is customized for different parts of the country, and participants continue to be "incredibly responsive to the message once it's explained," she says.

Greenwood says the keys locally and nationally are awareness, prevention and planting diverse species of trees. "Long term, maybe not moving firewood can become a social norm, like not littering became in the 1970s. We're the new 'Don't Litter.'"

The author has been published in national and regional magazines as well as daily and weekly alternative city newspapers. A gentleman farmer in Quakertown, Pennsylvania, he writes about people, social trends, historic preservation and 18th-century America, agrarian culture, land use, and sports and recreation topics.