Emerald Ash Borer (EAB) is an insect from Asia that is attacking the Midwest’s ash trees. EAB is a member of the metallic wood boring beetle family. It attacks all native, North American ash trees regardless of the tree’s health. Once an EAB infestation occurs, it kills the tree in three to five years.
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EAB Contacts and Information
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EAB is believed to have arrived in the United States in shipping pallets or cargo from eastern Asia approximately 10 years before it was discovered. It was first identified in the Detroit, Michigan area in July 2002 and then in Lucas County, Ohio, in February 2003. EAB has since been discovered in Michigan, Ohio, Indiana, Illinois, and Ontario Canada.
EAB is a slightly illusive insect because it spends the majority of its life under the bark. The larvae develop beneath the bark of ash trees and are flat, creamy white, with bell-shaped segments, and are about an inch long. Adult EAB are dark metallic green and a half-inch long.
EAB Life Cycle
From late spring through autumn adult beetles mate, and the female lays 60-90 individual eggs on ash tree bark. The eggs hatch 7 to 10 days later, and the larvae tunnel into the tree just beneath the bark where they feed on the live tissue of the tree. The larvae’s S-shaped feeding pattern, called galleries, disrupts the transport of water and nutrients, eventually killing the tree. Over the winter, the larvae remain under the bark. When warmer weather arrives, larvae enter the pupal stage and then transform into adults. The beetles emerge through the bark leaving behind 1/8 inch, distinctive D-shaped exit holes. The adults feed on leaves before mating and laying eggs, starting the cycle over again.
How to Tell if Your Tree Has EAB
There are several things that may indicate your ash tree has Emerald Ash Borer.
- Branch dieback at the top of the tree
- Vertical splits in the bark
- Sprouting on the trunk and at the base of the tree
- Scratched bark from woodpeckers feeding on the larvae
- Distinct 1/8 inch, D-shaped exit holes in the bark
- S-shaped, sawdust-packed galleries under the bark
EAB is very difficult to detect until a tree has been infested for at least a year because the larvae feed from the top of the tree first. When looking for EAB it is important to peel off the bark to look for the larvae and the galleries.