July Is Peak Month For The Emergence Of Emerald Ash Borer Pest (Photo) -07/09/25
SALEM, Ore. – Adult emerald ash borers (EAB) start emerging in Oregon in early June. However, the majority emerge this month (July). The size of a penny, adults are hard to spot and usually are only found in traps. If you think you’ve seen one, the Oregon Department of Forestry and Oregon Department of Agriculture ask that you first make sure it’s not a common lookalike bug.
“You can find a good description and photos comparing EAB to other common insects in Oregon that are also green in color at OregonEAB.com,” said ODF EAB Specialist Kat Bethea. “If you can capture the insect in a jar or other container that’s ideal, but at least try and take a clear, close-up photo. This helps us identify the insect in question much more easily.”
Bethea said people suspecting they’ve found EAB should report it over the phone to 1-866-INVADER or online at https://oregoninvasiveshotline.org/reports/create. Attaching a clear photo is important. Bethea said people who know they have an ash tree and notice a decline should report it the same way.
“Any ash tree can be infested, including native Oregon ash as well as non-native street, park and yard trees. Signs of infestation include thinning and yellowing leaves, bark splitting, D-shaped holes in the tree bark, and basal shoots,” said Bethea.
About EAB
A small, metallic-green beetle native to eastern Asia, EAB was first found in the U.S. in Michigan in 2002. It has since killed tens of millions of ash trees across the eastern United States, with death rates of 99 percent or higher.
ODF EAB Specialist Matt Mills said EAB’s larvae burrow into the bark of ash trees, causing canopy dieback and, ultimately, tree death.
“The half-inch beetle is often challenging to detect, especially in newly infested trees. That’s why ODF, in collaboration with the USDA Animal Plant Health Inspection Service, made sticky purple traps available to select landowners, primarily in the Willamette Valley. Those traps contain a lure and are checked every couple of weeks during the summer when adult EAB are flying.”
Mills said EAB is currently known to be in Washington County in the Forest Grove and Cornelius areas and a short distance into northern Yamhill County. It has also been found along Butte Creek between Marion and Clackamas counties, as well as in Woodburn, Mt. Angel and the Yoder area.
“You can find whether you’re in an EAB-infested area or close to one by checking an online map we’ve created. It shows the four counties where firewood from hardwood trees cannot be removed. That quarantine also covers any part of ash, olive or white fringetree (Chionanthus virginicus),” said Mills.
For people who want to protect their ash trees before they become infested, there is an effective insecticide that can be injected at the base of the tree’s trunk, said Mills.
“It gets taken up into the tree canopy and is quite effective at protecting the tree from both adults and larvae.”
Mills said treatments must be done every two or three years by a licensed pesticide applicator.
“That’s why we recommend only treating high-value trees in good condition,” he said.” Ash trees planted in the wrong place to reach their mature size, such as under powerlines, should be removed as time and funds permit and replaced with species that aren’t susceptible to EAB.”
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