Why is EAB important?
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Emerald Ash Borer (Agrilus planipennis) is an invasive wood boring beetle that feeds on the tissues under the bark of ash trees (Fraxinus spp) and kills them. The metallic green beetle is native to East Asia and was accidentally imported to the United States within the wood of shipping crates from China. EAB was first discovered in North America near Detroit, Michigan in 2002. Since then the beetle has spread to several eastern and midwestern states, including Wisconsin. EAB has also been found in Canada.

EAB is not a threat to human health but it does threaten our forest and urban tree populations.

EAB is 100 percent fatal to our native ash trees of any size, any age, healthy or unhealthy, (according to research by Michigan State University and the US Forest Service).

The larva (the immature stage of EAB) spends its life inside ash trees, feeding on the inner bark where we cannot see it. This feeding disrupts the trees' ability to transport water and nutrients, causing the tree to starve and eventually die.

On its own, the beetle will only fly a few miles. However, it is easily and quickly transported to new areas when people inadvertantly move emerald ash borer larvae inside of infested firewood, ash nursery stock, and other ash items.

A tree that has been attacked by EAB can die within 2-4 years. It is estimated that more than 50 million ash trees are dead or dying in the Midwest because of this insect.

Wisconsin forests contain more than 770 million ash trees, nearly 7 percent of the tree population. In urban areas, we estimate that ash make up, on average, 20 percent of trees.



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The adult Emerald Ash Borer (beetle) on a U.S. penny. Photo by Krista Hamilton, WI DATCP.


Example of EAB larva.


Example of the feeding galleries produced by emerald ash borer larvae under the bark. Larvae will feed and grow for 1 - 2 years under the bark, depending on conditions and the ash tree host.



After the larvae grow into adult beetles within the ash tree, they chew through the tree bark to the outside, leaving behind tiny D-shaped exit holes.

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