Emerald ash borer expands into Beaverton, Salem and rockcreek area

BEAVERTON, Ore. (KTVZ) --- The emerald ash borer has been confirmed in several new locations across northwest Oregon, including first-time detections in Beaverton, Salem and the Rockcreek area. The Oregon. Department of Forestry announced the findings today after traps set earlier this spring were checked in July.

The exotic beetle infests and kills ash, olive and white fringetrees. The pest was also rediscovered at a school parking lot in east Portland and at Hazeldale Park west of Beaverton, where it had previously appeared.

The emerald ash borer was first detected in Oregon in June 2022 in Forest Grove. Since then, the infestation has spread to Clackamas, Marion, Multnomah, Wash. and Yamhill counties. It is considered the most destructive forest pest ever seen in North America, responsible for killing hundreds of millions of trees across the United States and Canada.

The larvae kill trees by feeding on living tissue located under the bark. Forestry officials noted that all American and European ash species, including native Oregon ash, are susceptible to the beetle.

New detections were confirmed at Bethany Lake Park in the Rockcreek area and at the Oregon. Garden in Silverton. The beetle was also found along the Banks-Vernonia State Trail, marking the first time the pest has appeared in an Oregon state park. Officials at the Jackson Bottom Wetlands Preserve in Hillsboro reported a likely detection, though it is currently awaiting official confirmation from the state.

The City of Salem has spent several years preparing for the infestation by inventorying nearly 4,000 ash trees along streets and in natural areas. The city halted the planting of new ash trees and began pre-emptive removals of trees in poor health. In 2025, officials began injecting insecticide into 600 trees in the northern part of the city to protect them from the beetle.

Beaverton officials began mitigation efforts after receiving a one-year grant from the Tualatin Soil and Water Conservation District in October 2024. The city used the funds to treat 600 of its 2,000 inventoried ash street trees. Jered Lane, Beaverton city arborist and public works supervisor, said the city has also planted 60 new street trees with the help of volunteers.

“In response to the threat of EAB, in 2026 we have so far treated 22 city-maintained natural area trees 20 inches in diameter and larger and planted more than 2,000 native trees and shrubs,” Lane said. “We are continuing to monitor ash street trees throughout the city with regular inspections, respond to concerns about possible cases in Beaverton and educate the public about EAB.”

Kat Bethea, an emerald ash borer specialist with the Oregon Department of Forestry, said the adult beetles are only active from June through September. Signs of an infested tree include thinning or yellowing leaves, bark splitting, D-shaped holes in the bark and shoots growing from the trunk or branches. “If you can capture the beetle in a jar or other container that's ideal, but at least try and take a clear, close-up photo,” Bethea said. “This helps us identify the insect in question much more easily.”

A quarantine currently exists in the five infested counties, prohibiting the removal of firewood from hardwood trees. Matt Mills, an emerald ash borer specialist with the forestry department, said the quarantine also covers any part of ash, olive or white fringetrees. Mills noted that insecticide injections at the base of a trunk can be effective if repeated every two or three years by a licensed applicator.

“That's why we recommend only treating high-value trees in good condition,” Mills 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.”

The City of Salem plans to inject insecticide into another 600 trees next spring. Residents who suspect they have found an emerald ash borer are asked to report the sighting by calling one-866-INVADER or by filing a report online at the Oregon Invasive Species Council website.