Emerald Ash Borer (EAB) Information & Resources

Emerald Ash Borer

Image Credit: Marianne Prue, Ohio Department of Natural Resources - Division of Forestry, Bugwood.org. Obtained from U.S. Department of Agriculture - aphis.usda.gov

Update: Oregon Department of Forestry March 20, 2023

The Oregon Department of Forestry has just released their first Bulletin of Emerald Ash Borer (EAB) news as of March 20, 2023. Of the 8,500 trees surveyed, 95% of which were located in neighboring Washington County, 39 trees had confirmed EAB presence. Surveys through March 20, 2023 appear to show that Emerald Ash Borers have yet to spread beyond Washington County.

See the official bulletin (PDF).


The Emerald Ash Borer (Agrilus planipennis) was first observed locally on June 30, 2022 in Forest Grove. It is an invasive, emerald green beetle species that has killed countless ash trees in the midwest and on the east coast over the last 20 years. Locally, the trees most at risk are the native Oregon ash species (Fraxinus latifolia), as well as non-native ash species commonly used as street and landscape trees in Oregon City.

Adults are a bright, metallic "emerald" green. They bore into ash tree bark, causing tree canopy thinning and dieback because they disrupt the tissues that conduct water and nutrients throughout the tree. These beetles leave characteristic "D"-shaped exit holes in ash tree bark approximately 1/8-inch in diameter. They emerge in late May and June. Heavy infestations can kill susceptible trees in a couple of years.

Emerald Ash Borer Exit Hole

Image: Example of the characteristic D-shaped Emerald Ash Borer exit hole, next to a pencil tip for size comparison. Credit: Kenneth R. Law, USDA APHIS PPQ, Bugwood.org, CC BY 3.0.


Trees provide a great many benefits to our community. Maintaining the City's tree canopy is a major priority for the City and many of its residents. While tree loss due to the invasion of Emerald Ash Borers is a major concern in itself, the overall impacts of Emerald Ash Borers in Oregon City will likely be much wider.

Ash trees are a vital component of natural areas along rivers and streams, and once they begin dying as EABs spread, natural habitats will change very quickly. Dead, dying, and diseased trees can also cause damage to property and create safety hazards for people. Please refer to our Tree Removal resources links on this page for more information about removing and replacing dead, diseased, dying, and hazardous trees in Oregon City.

Oregon AshAll North American species of ash are susceptible to the Emerald Ash Borer, as are white fringetrees (Chionanthus virginicus) and olive trees (Olea europaea).

Image: Example of an Oregon Ash (Fraxinus latifolia) tree, which among other Ash species, is a prime target for the Emerald Ash Borer. Image courtesy of Friends of Springbrook Park.

What Can You Do?

Assist with Detection

Don't Move Firewood!

If possible, buy or obtain your firewood as locally as possible. Just moving firewood from one town to the next could provide Emerald Ash Borers a free ride to invade a new area.

Care for Ash Trees

If you have ash trees or any other susceptible species, take care of them. Emerald Ash Borers are most attracted to trees that are under stress due to poor care or maintenance.

  • In the summertime, drought is a primary stressor for trees. To counteract this, water and mulch both young and mature trees.
  • Pruning cuts can also send stress signals to pests. If you have ash trees, avoid pruning them during the height of Emerald Ash Borer activity, which is April through October.

Local Tree Care Providers

If you are a local tree care provider, learn about the telltale signs of Emerald Ash Borer presence in the trees you care for. Report sightings and dispose of wood waste properly.


Share what you've learned with others! Especially those who have ash trees or other susceptible species. Inform people you know who use and store firewood about how they can help reduce the spread of the Emerald Ash Borer.

More Information

Email the Planning Division or consult the Adopted Street Tree Species List (PDF) for questions about tree planting alternatives.

Ash Leaves

Image: Examples of the leaf structures and patterns for various ash tree species. Image courtesy the NJ Department of Agriculture.

What Else Is Being Done?

The Oregon Department of Forestry (ODF), Oregon Department of Agriculture, and their community partners, have been preparing for this event for the past several years:

In 2018, the Oregon Invasive Species Council produced the Emerald Ash Borer Readiness and Response Plan.

Oregon Department of Forestry is providing ongoing education and guidance to cities and towns on best practices for slowing the spread of Emerald Ash Borers. ODF has also been collecting and saving Oregon ash seeds to preserve for future planting, and to test them for resistance to Emerald Ash Borers. In addition, ODF has been setting traps across the state to monitor the spread of Emerald Ash Borers.

Note: This page was adapted with special consideration for Oregon City codes, policies, and programs from the Emerald Ash Borer (EAB) page on the City of Portland website.