ORTLAND, Ore. – The emerald ash borer (EAB), a tiny green beetle responsible for killing millions of ash trees across North America, has been confirmed in six new sites in northwest Oregon this summer — including a site in southeast Portland — prompting state officials to expand the quarantine zone to include all of Multnomah County.
EAB was first detected in Oregon in 2022 at a Forest Grove school. Since then, state and local agencies have monitored its spread using sticky purple traps and tree inspections. This year’s detections were found at Hazeldale Park near Beaverton, Killin Wetlands near Banks, rural Yamhill County, two locations in Clackamas County, and at the David Douglas Aquatics Center in Portland, where a private arborist spotted a dying ash tree and alerted authorities.
City and state inspectors confirmed EAB activity by identifying characteristic tree damage and capturing an adult beetle, later verified by federal labs.
“The pattern of spread we’re seeing matches what has happened in the eastern U.S. — slow at first, then rapid and widespread,” said Cody Holthouse of the Oregon Department of Agriculture. “Finding a single beetle in a trap usually means there are many more in the area.”
Officials urge Oregonians to help slow the spread by following quarantine rules: do not move ash firewood or plant material outside the five-county quarantine area (Clackamas, Marion, Multnomah, Washington, and Yamhill counties).
Communities are taking action to protect valuable ash trees. Beaverton and Hillsboro are treating hundreds of healthy public ash trees with an effective systemic insecticide, while Salem and Portland have begun similar efforts. Portland also preemptively removed poor-condition ash trees and adopted a long-term strategy to diversify its urban forest.
Residents are encouraged to inspect their ash trees for signs of infestation — including canopy dieback, bark splitting, and D-shaped exit holes — and to report suspected EAB sightings online at OregonInvasivesHotline.org or by calling 1-866-INVADER. High-value ash trees can be protected by licensed applicators using injections every 2–3 years.
“Early action is critical,” said ODF EAB Specialist Kat Bethea. “Treat healthy trees now, replace small ash trees if needed, and avoid moving firewood to help slow EAB’s spread and protect Oregon’s urban and native forests.”
