First Emerald Ash Borer (EAB) confirmed in Oregon

A sole adult EAB lives less than 30 days after emergence. Image: James Zablotny Ph.D Source:

On June 30, the state of Oregon Department of Forestry confirmed the first report of Emerald Ash Borer in the region. The devastating invasive insect was identified in Michigan in 2002 and has since spread throughout the Midwest and along the Atlantic coastline, and now it has just been discovered in Forest Grove, Oregon. Its arrival will likely threaten both native and non-native ash trees in the region’s forests and urban areas.

What’s at stake?

EAB larvae bore galleries in the ash wood, pupate within these gallery spaces, and emerge through holes in the spring. Image: Daria Gosztyla

Emerald ash borer (EAB) is one of the costliest and most ecologically devastating species to North American forests. In the Pacific Northwest, the Oregon ash (Fraxinus latifolia) has an important ecological role along streams, in wetlands, and in other natural areas. Cultivars of non-native ash trees are planted and become large shade trees in urban areas. The establishment of EAB in the Pacific Northwest will have a negative impact on riparian habitats and urban forest canopy cover, though it is tough to predict exactly how this will all play out. State and federal agencies across the US and Canada have not been successful at containing or eradicating the insect. In other states, EAB has proven its potential to cause the local extinction of ash species within a decade of arrival.

You can read more about the arrival of Emerald Ash Borer in Oregon here.

Learn more about anticipated impacts of EAB on the region here.

Catch up on the state of Oregon’s Emerald Ash Borer Readiness and Response Plan here.

What can we do?

Now more than ever, it’s important that we work together to identify and slow the spread of EAB throughout the state of Washington.

Thinning crowns in ash trees are often the first sign of possible EAB infestation. Image: Daria Gosztyla
  1. Learn to identify the emerald ash borer and the signs of an infestation: Often, the most common sign of infestation is crown dieback, small D-shaped exit holes, and suspicious trunk sprouting on true ash trees (Fraxinus). Although rare to spot, the adult beetles can be identified by their metallic green color and are typically about one half-inch in size. Here is a guide to help separate EAB from its doppelgangers.
  2. Report any suspect EAB sightings to the Washington Invasive Species Council here.
  3. Understand the risk of EAB in your community through a tree inventory: Documenting tree species can help understand how vulnerable your local community is to the loss of ash trees from EAB.
  4. Don’t move firewood: Prevent the rapid spread of EAB by buying firewood locally.
  5. Don’t plant ash trees: Remove ash trees from your community’s tree planting list and strive to increase your community’s tree diversity to be more resilient to future pest outbreaks.
The D-shaped exit hole matches the body contour of the EAB; a flat back and round underside. Image: Daria Gosztyla

Pest readiness in the Pacific Northwest

The Urban and Community Forestry programs in Washington and Oregon are working together to monitor for invasive insect species and prevent them from establishing in our ecosystems, if possible. Below you can read more about ongoing projects to prepare and protect the region’s urban forests.

  1. Urban Forest Pest Readiness Project: In partnership with the Washington Invasive Species Council, the DNR Urban Forestry program developed the Urban Forest Pest Readiness Playbook to help communities prepare for invasive pest outbreaks. You can read more about the ongoing project here and learn about actions that your town and community can take to respond to a pest outbreak.
  2. Preserving genetic diversity of ash trees: Scientists from the USDA Forest Service are working to save the gene pool of Oregon ash trees (Fraxinus latifolia) by collecting seed from native ash species for long-term storage. Samples from Washington are being collected this year. See why this effort is so important to the future of our forests in this video from ODF.
  3. Washington Statewide Tree Inventory: The state of Washington Urban and Community Forestry program is developing a statewide urban tree database to understand the diversity of tree species throughout the state and to anticipate and respond to forest health issues. This statewide inventory was just recently developed and has not been analyzed for Emerald Ash Borer vulnerability. More information will be provided in future editions of Tree Link. Does your community have a tree inventory? Please contact our program at to get involved.