What is the emerald ash borer?

A small, metallic green beetle from Asia whose larvae tunnel under the bark of ash trees. It was first found in North America in 2002 and has killed hundreds of millions of ash trees.

How can you tell if an ash tree has emerald ash borer?

Look for a crown thinning from the top, small D-shaped exit holes in the bark, pale patches where woodpeckers have stripped bark, and clusters of sprouts on the trunk.

Can an infested ash tree be saved?

Sometimes. Trees treated early by a certified arborist can often be protected, but heavily infested trees usually die within a few years.

How does emerald ash borer spread?

The adults fly short distances on their own, but the beetle has spread much farther in firewood and other wood moved from infested areas.

What’s happening to ash trees?

White ash has one of the most unusual fall colors in the East, a purple to maroon that stands out among the reds and yellows. It’s also disappearing from many forests and streets, because of a small green beetle.

The emerald ash borer

The emerald ash borer is a metallic green beetle about half an inch long, native to Asia. It was first found in North America near Detroit in 2002, most likely arriving in wooden shipping material, and it has since spread across much of the eastern and central U.S. and beyond, helped along by moving infested firewood.

How it kills a tree

The adult beetles do little harm. Their larvae are the problem: they tunnel just under the bark, cutting through the layers that carry water and nutrients. Once a tree is heavily infested, it usually dies within a few years. North American ash trees have little natural defense against it, and it has killed hundreds of millions of them.

Signs of an infested tree

The crown thins from the top down, with dead branches up high. Small D-shaped exit holes, about an eighth of an inch across, show up in the bark. Woodpeckers flake off patches of outer bark to get at the larvae, leaving pale blotches. Under loose bark, the larvae leave winding, S-shaped tunnels. Stressed trees often sprout clusters of shoots from the trunk.

What it means for fall color

In many eastern woods, ash was a common tree, and its purple and yellow were part of the fall mix. As ash dies off, that color is fading from those forests, and standing dead ash is a common sight along roads and trails.

What helps

The biggest thing anyone can do is not move firewood. Buying and burning firewood near where you use it keeps the beetle and other forest pests from hitching a ride to new places. Valuable ash trees can often be protected with treatments applied by a certified arborist, and researchers are releasing tiny, stingless wasps from the beetle’s native range that attack its eggs and larvae. If you think you’ve found the beetle in a new area, your state forestry agency or extension office will want to know.