three forest pest specialists look at blonding of ash trees

Now is a great time of year to look for signs of forest pests like emerald ash borer, Asian longhorned beetle and hemlock woolly adelgid in your trees. With leaves off the trees, it can be easier to spot some tell-tale signs of a pest infestation. Here are some things to look for.

Emerald Ash Borer (EAB)

  • EAB only attacks true ash trees. Learn how to identify ash trees.
  • EAB larvae over-winter just under the bark of ash trees. Woodpeckers have been known to forage for the larvae by stripping off the outer bark. This activity leaves visible light tan patches of inner bark—known as “blonding.”
  • Sometimes, the bark of ash trees will split or fall off, and you can see the galleries left by larvae under the bark. EAB larvae leave s-shaped, or serpentine, galleries behind as they grow.

Asian longhorned beetle (ALB)

This pest has not yet been found in New Hampshire.

  • ALB are different from EAB in that they attack many types of trees.
  • Females chew oval to round pits in the bark to lay their eggs.
  • Larvae feed under the bark and bore deep into the wood to pupate.
  • When adults emerge from the tree (in July or August), they leave behind 3/8 inch or larger round exit holes.

Hemlock woolly adelgid

We need your help finding these pests!

Report any suspicious trees. And learn more about these and other forest pests at