agrilus planipennis is the scientific name of this terrible menace that has devastated ash trees across the Midwest. Ohio has been particularly hard hit since we have had so many ash trees in our parks and forests. A native of Asia, EAB was first seen in the Detroit region but has now spread across Ohio and other states.
Symptoms: The larvae lie dormant during winter in the tree and then emerge as adults in the spring, leaving D-shaped exit holes. Like the birch borer, EAB larvae disrupt the movement of sap in the tree. The damage can be seen in the s-shaped rings under the bark of the trees. The shape of the exit holes in the trunk is a key diagnostic feature to distinguish EAB from native borers. The exit holes of emerald ash borer are distinctly D-shaped and about 1/8–1/4 of an inch.
More information: Ohio State University Extension and Forestry, Ohio DNR