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Keep An Eye Out For Invasive Forest Pests

by Stacy Kilb

The Massachusetts Department of Resources is encouraging everyone to check trees for signs of invasive forest pests. Tree-killing insects like Asian Longhorned Beetle (ALB) and Emerald Ash Borer (EAB) are a serious threat to forest ecosystems across Massachusetts. 

“Early detection of Asian longhorned beetle or emerald ash borer can make all the difference in preventing these forest pests from getting established in a new area. Now is a great time to get out there and inspect trees, because the weather is nice but you can still see tree limbs because the leaves still haven’t completely unfurled.” says Jennifer Forman Orth of the Mass. Department of Agricultural Resources. “We’re asking everyone to take just 10 to check the trees in their neighborhood, local park, or forest, and to report any suspicious tree damage.”

Since 2008, more than 30,000 trees have been lost to the ALB infestation in the greater Worcester area. ALB slowly kills trees by tunneling deep into the heartwood, destroying them from the inside out. If ALB were to become established throughout Massachusetts, it would not only have negative impacts on forest ecosystems, but would also impact fall foliage tourism, the maple sugaring industry, and could render formerly tree-lined neighborhoods shadeless for years to come. Emerald Ash Borer is the newest wood-boring pest to be found in Massachusetts. It was first discovered in Berkshire County in August 2012, and was more recently found in Essex County in November 2013. Although EAB only attacks ash trees, it can kill a mature ash in just a few years, and moves very quickly from one tree to the next.

“Unfortunately, EAB has proven too difficult to eradicate, but through early detection we can slow the spread of this pest and give communities time to prepare and protect valued ash trees.” says Forman Orth. “One way to do this is to join our citizen science project, Massachusetts Wasp Watchers. Using teams of volunteers, Wasp Watchers tracks a native non-stinging wasp that preys on EAB and other related beetles and uses it to detect new EAB infestations.”

Exit hole left after the adult Asian Longhorned Beetle chews its way out of a tree.

Exit hole left after the adult Asian Longhorned Beetle chews its way out of a tree.

The Wasp Watchers season doesn’t start until July, so until then, everyone can help by taking 10 minutes now to check the trees in their neighborhood. To check for signs of ALB, look for three things: 1) perfectly round exit holes, a bit smaller than a dime, 2) ½ inch oval divots in the bark left by female beetles digging sites to lay eggs in, and 3) “frass” – a sawdust-like material found at the bases of trees or in the crooks of branches. ALB infests many common hardwood trees, particularly maple, elm, willow, birch, horse chestnut, ash and cottonwood. It will not infest any softwoods like pine, fir or spruce, and does not attack other hardwoods like oak or cherry.

“Blonding” of an ash tree caused by woodpeckers seeking Emerald Ash Borer larvae.

“Blonding” of an ash tree caused by woodpeckers seeking Emerald Ash Borer larvae.

To check ash trees for EAB, look for these three signs: 1) a majority of dead branches in the upper third of the tree’s canopy, 2) D-shaped holes left in the bark when the beetle bores its way out, and 3)“blonding” – stripping off of the bark on the trunk and main branches, exposing a layer of blonde wood. Blonding is actually damage done by woodpeckers seeking the EAB larvae, which bore just under the bark.

In addition to checking trees for signs of forest pest damage, here are more tips to prevent the spread of invasive pests:

  • Tree-killing pests can lurk in firewood, brush and tree debris, and wood packaging material. Help slow the spread of pests by buying, using, and disposing of wood products locally. Don’t move firewood!
  • Burn it where you buy it! Obtain firewood near the location where you will burn it, or be sure the wood you transport was kiln-dried to kill any unwanted hitchhikers. Respect all state and local regulations on the movement of firewood and other unprocessed wood.

To report suspicious tree damage or insect sightings, or to learn more about these pests, visit

To sign up for Massachusetts Wasp Watchers program and help detect new EAB infestations, visit

About the Author

Stacy Kilb is the Asian Longhorned Beetle Outreach Coordinator for the Massachusetts Department of Agricultural Resources (MDAR). Before working for MDAR, Stacy worked as a Department of Conservation and Recreation Park Interpreter, and received her Master of Education from Suffolk University. She may be reached at or (617)626-1764.