​If you’re walking in the woods or maybe even traveling along a road this spring in Indiana, you may come across some trees that look like the one in the photos. Clearly, something unusual is going on here. What made the bark change color so quickly, and why are there holes in the bark?

The answer to both of those questions for ash trees around the state is Emerald Ash Borer and woodpeckers. As Emerald Ash Borer spreads across Indiana, the population of Emerald Ash Borer larvae overwintering under the bark of ash trees can quickly increase. These grubs provide a tasty treat and important winter and early spring nutrition to hungry woodpeckers.

Woodpeckers of several species are experts at detecting and extracting these grubs by pounding holes in tree bark. Ash bark is generally gray on the surface, but the inner bark is a light corky tan color. Once the woodpeckers find the EAB larvae, their excavation activities flake off the outer bark to expose the lighter colored inner bark. This is actually one of the best indicators of the presence of Emerald Ash Borer in a tree. The woodpecker activity often starts in the upper main stem and branches of ash trees, but as the population of EAB larvae in the trees increase, the woodpecker activity spreads down the trunk of the tree. Trees with this much inner bark exposed indicate an advanced infestation of EAB and signal ash tree mortality in the next year or two.

If you would like to learn more about ash trees and the Emerald Ash Borer, visit the Purdue Emerald Ash Borer website.

Resources
Arrest That Pest! – Emerald Ash Borer in Indiana, The Education Store
Purdue Extension – Forestry & Natural Resources website with search bar, place “Invasive Insect”
Emerald Ash Borer, Indiana Department of Natural Resources (IDNR)
Emerald Ash Borer in Indiana​, Purdue Extension
New Hope for Fighting Ash Borer, Purdue Extension – Forestry and Natural Resources Got Nature? blog

Lenny Farlee, Extension Forester
Purdue University Department of Forestry and Natural Resources