Emerald Ash Borer in Southwest Ohio: A Timeline to 2026

The stumps of ash trees are easy to find in southwest Ohio. This post follows the beetle that killed those trees from its first Hamilton County confirmation to today. Dates come from Ohio State University (OSU) Extension, Cincinnati Parks, the City of Forest Park and the Kentucky Division of Forestry. Where a source gives no date, the post says so.

When did emerald ash borer reach southwest Ohio?

OSU Extension says the beetle was confirmed in Hamilton County in 2007. It had arrived in North America earlier: OSU says it came to the Detroit, Michigan area in the late 1990s and was first detected in 2002. OSU’s Ashley Kulhanek writes that Ohio was “very close to the epicenter.”

The emerald ash borer is an invasive beetle whose larvae feed under the bark of ash trees. The timeline below shows what the sources record.

What did Cincinnati and Forest Park lose?

Cincinnati Parks Urban Forestry compared its tree canopy in 2000 and 2010. The city found a 2 percent decrease over those ten years and says the driving force behind the loss was the arrival of the invasive species the Emerald Ash Borer. Its page also says that eight communities had a considerable loss of 6 percent or more.

Forest Park, a Hamilton County city, says its urban forest has taken a beating. The city ties the decline to aging trees and to various infestations, naming emerald ash borer, and says large segments of its trees have died or are dying.

These are city statements, not scientific measurements by this site. They show how the pest shows up in official language across the county. For the local picture in the city, see stump grinding in Cincinnati.

What is bush ash?

Bush ash is multi-stemmed regrowth from the base of a dead ash tree or stump. OSU Extension says ash regeneration “became evident in southwest Ohio as early as 2008.” OSU explains the cause plainly: EAB kills only the above-ground part of an ash, so new growth could resprout from the base.

The new stems did not stay safe. OSU says they were attacked as soon as they reached enough girth to support EAB larvae. That kept a supply of beetles even as their numbers fell.

OSU compares it to chestnut blight. The fungus does not kill the American chestnut’s roots, so sprouts keep coming back in the woods. Then the cycle starts again.

The glossary has short entries for bush ash and stump sprout. The guide on dead ash tree stumps covers what to do about them.

Did the beetle disappear?

No. OSU Extension says the beetle populations crashed once most large ash died, but they never went to zero. Some regenerated ash grew very large with no sign of dieback. OSU says that was because beetle numbers were extremely low.

Then, OSU wrote in 2023, “over the past few years, EAB has experienced a reversal of fortune.” Multi-stemmed ash in the southwest part of the state began to lose stems. Trees that had stopped being treated also began to show signs of infestation. OSU reports jagged woodpecker holes again on ash trunks and branches, and leaf-notching damage it suspects came from adult beetles.

OSU’s July 2026 article, “Emerald Ash Borer Still Infesting Trees,” makes the same point from a different angle. Even though the initial wave has long passed, the beetle is still present in forests and landscapes.

What does this mean for my yard?

If you have a dead ash stump, three things follow from the sources.

1. Shoots are normal. OSU documented them in southwest Ohio as early as 2008.
2. Shoots can be attacked. OSU says the new stems were attacked once they grew thick enough.
3. The beetle is not gone. OSU says EAB will be with us for years to come.

The sources do not say what to do to stop shoots. They also do not say whether grinding the stump removes the growth. The guides on will a stump grow back and do roots die after stump grinding cover those questions in general terms. If you use any chemical product, follow the product label.

Where the ash was on a tree lawn, the city may have a say. See who owns the stump on the tree lawn. For the current status in Ohio and Kentucky, read emerald ash borer status in Ohio and Kentucky.

Next step

To read the full guide to ash trees and stumps, see ash trees, emerald ash borer and stumps. Call (513) 587-6772 or send photos for a free estimate.