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Articles from our Landowner Newsletter

A River (or Creek) Runs Through It: Conservation to Improve Water Quality. Read more.

 Fostering Farm Enterprise: VLT's Farmland Access Program. Read more.

Sandy Witherell and Pieter van Loon

Kent Family Farm: One Familly's Experience with Timber Harvesting. Read more.

sweat beeGetting Started with Pollinators: Managing Land for Pollinator Habitat. Read more.

manure drag lineKeeping Nutrients in the Soils: Manure Injection and Aeration. Read more.

soilSoil Recovery after Irene: Questions and Answers with Heather Darby. Read more.

emerald ash borerInvasive Insects: Achilles heels of the northern forest. Read more.



by Joan White

Whether it’s seeing strange sawdust collecting at the base of a maple or the cracking bark of an ailing ash, landowners often notice when something out of the ordinary is happening to their trees.

Vermont’s forests are at risk if two invasive pests arrive—the Emerald Ash Borer or the Asian Longhorned Beetle. Private citizens and landowners have been the first to spot the Emerald Ash Borer in Connecticut and the Asian Longhorned Beetle in Massachusetts. Vermont landowners can also play a key role in protecting our forests.

Emerald Ash Borer larvae create “S”-shaped galleries under the bark of infested ash trees. Photo courtesy of Edward Czerwinski, Ontario Ministry of Natural Resources, Bugwood.org
Tree damage

What’s at stake

Emerald Ash Borer larvae feed on the tender tissue directly under the bark of ash trees, which eventually cuts off the flow of carbohydrates and nutrients. Urban areas and places near streams, rivers, and lakes, where ash grow abundantly or were planted, are especially at risk of Emerald Ash Borer, which can kill up to 99 percent of the ash trees in an infested area.

Asian Longhorned Beetle larvae, on the other hand, burrow deep into the heartwood of many different species. Up to one third of the trees in Vermont could become hosts to Asian Longhorned Beetle. Vermont’s sugarmakers are especially concerned about this pest because its favorite tree to feed on is maple.

Trees infested with these pests almost always die, and infestations spread quickly to trees nearby.

For both insects, early detection will allow federal, state, and local land managers to jump into action, limiting damage. Just as private citizens helped identify these invasive pests in other New England states, they are important to Vermont’s monitoring efforts.

“VLT partners with the state in monitoring and response,” says Caitlin Cusack, forester and VLT regional stewardship manager. “VLT staff are here to support our landowners in making good decisions. Informed landowners and citizens are our best defense—they are the eyes and ears on the ground.”


The Asian Longhorned Beetle leaves behind holes smaller than a dime. Photo courtesy of Daniel Herms, The Ohio State University, Bugwood.org
Exit hole

What to look for

First, landowners should look for signs of stress in their trees. Cracking bark and bushy branches emerging from the base and trunk of ash trees may indicate the presence of Emerald Ash Borer. Look for woodpecker stripping of bark, which makes the bark appear lighter especially toward the top of the tree.

If the tree is infested, there may be unique “S”–shaped paths where the Emerald Ash Borer larvae has chewed through wood under the cracked bark.

Asian Longhorned Beetle causes branches to die back and premature fall foliage. There may be buildup of what looks like sawdust, but is in fact insect waste called “frass,” around the base and in the crotches of branches.

Asian Longhorned Beetle exit holes are easy to spot. The perfectly round holes are strikingly similar to a tap hole and are smaller than a dime; a pencil can be inserted at least one inch into the hole. There are several “look alike” native species of wood-boring insects, so landowners can check vtinvasives.org/tree-pests/report-it to verify the sighting before reporting it.

What to do

Mollie Klepack, the Forest Pest Outreach Coordinator at the University of Vermont Extension program, emphasizes reporting potential invasive insect activity: “We are hoping to detect infestation as early as possible. Knowing where it occurs will allow us to slow the infestation and target land management.”

If you see signs of these pests, contact This email address is being protected from spambots. You need JavaScript enabled to view it. at (802) 861-6504, or any member of VLT’s stewardship crew. If you love Vermont’s woodlands and want to take an active role in protecting them, join the First Detectors Program to learn how to recognize these pests and help educate your community. More information at: vtinvasives.org/first-detectors.


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