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Emerald Ash Borer

-Marianne Prue, Ohio Department of Natural Resources

Early January 2024 Fayette County Conservation along with Fayette County Secondary Roads cut down multiple dead/dying green ash trees from the courthouse lawn in West Union, IA. As we were cutting and chipping these trees up, I started thinking about who planted them, and what they would think of what we were doing on that day. (I have a feeling they would not be very happy.) I talked to a few people who owned and worked at businesses around the courthouse square, and they all asked what we were doing and why we were doing it. We unfortunately were cutting the trees down due to a non-native invasive beetle who originates from northeast Asia; the emerald ash borer. In it’s native lands in Asia this species typically only infects already dying ash trees, but when it was introduced to the United States (Just as most nonnative species) it had a hay day, and started decimating everything in it’s path. This species was spotted in Michigan in 2002 and most likely arrived from a shipment containing contaminated ash wood. Over the last 20 or so years now this beetle has spread and killed millions of our North American ash trees and has caused millions of dollars in damage. Many trees planted in parks and along city streets are ash trees because they are a beautiful tree with pretty bark and leaves as well as being a good height tree when they are fully grown and healthy.

-David Cappaert, Michigan State University

The way that this beetle kills these ash trees is the larvae eating the outer part of the tree just under the bark. This area of the tree is where all the nutrients are carried up to the leaves and back down to the roots. As this area gets eaten away more and more by the beetle larvae the tree is unable to transfer nutrients and it slowly starts to die. A newly infected tree can usually be seen dying back at the top of the tree first and slowly dies back further and further down the tree as time goes along. If you were to peel the bark away from the tree you would be able to see corkscrew looking channels where the larvae chewed its way around under the bark.


-Channels dug by the emerald ash borer (Agrilus planipennis) in a deceased ash tree.

NPS photo/A.Smith


Cost: If you look out in your front or back yard or even visit your favorite park it most likely has an ash tree in it. Insecticide can be injected into the tree to kill the beetles, but it is very costly to do and has to be done every couple of years which could possibly not actually solve anything in the end. (Hopefully if treated enough years the beetles will have moved on, and they might not become infected simply because there are no more beetles left in the area, but if it does become infected thousands of dollars could have been spent already.) If the trees are not treated in most cases, it is extremely costly to have a tree cut down especially in town due to all of the logistical things that come into play. (Powerlines, houses, bucket trucks, vehicles, street closures to name a few.)


What can I do? One of the best things you can do is to gain awareness of the importance of not bringing non native things into your area. It is possible for this beetle to transfer to other areas of the country through firewood so if you travel and camp much, please don’t transport firewood even if it isn’t ash. You never know what might be hiding inside of it!

The future plans for the courthouse lawn will include planting new trees as well as planting a micro prairie which I will blog about in a later post so keep checking back for more info!


If you have questions about this blog post, please reach out to Isaac at

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