Emerald Ash Borer (EAB)

Find information about the Emerald Ash Borer, an invasive insect species.
A photograph of an adult metallic green colored Emerald Ash Borer insect on a leaf.
The adult Emerald Ash Borer is striking in appearance and smaller than a dime. Photo: Leah Bauer, USDA Forest Service Northern Research Station, Bugwood.org


Emerald ash borer (Agrilus planipennis) (EAB), is an invasive insect species. It has killed hundreds of millions of ash trees in the US Midwest and East Coast since it was first detected in 2002. 

The first observance of EAB on the west coast occurred on June 30, 2022, in Forest Grove, Oregon. 

All ash species (Fraxinus spp.) are at risk from EAB, including the native Oregon ash (Fraxinus latifolia). This tree species is a vital part of natural areas along rivers and streams in Western Oregon. This habitat will change as EAB kills Oregon ash trees.

Non-native ash species planted as street and landscape trees are also at risk. EAB will damage ash trees in Oregon cities and towns.

Emerald Ash Borer Identification

This insect gets its name because adults are a bright, metallic green. The adults live for a short time during summer months. You are more likely to see damage to ash trees as described below.

Emerald Ash Borer Damage

  • The beetles cause canopy thinning and dieback. They disrupt the tissues that conduct water and nutrients in the tree.
  • EAB leaves characteristic “D”-shaped exit holes in the bark when they emerge in late May / June. The holes are about 1/8-inch in diameter. 
  • Heavy infestations can kill susceptible trees in a couple of years. 

Susceptible Tree Species

All species of ash trees (Fraxinus spp.) are at risk.

White fringetree (Chionanthus virginicus) and olive trees (Olea europaea) may also be at risk.

See an interactive map to find ash trees planted in Portland Parks and rights-of-way.

What Can You Do?

1) Help with Emerald Ash Borer Detection Efforts

2) Don't Move Firewood

See this Public Service Announcement from Michigan. The video details the risk of spreading emerald ash borer by moving firewood.

If possible, buy or obtain your firewood as locally as possible. Even moving firewood from one town to the next town could provide EAB with a free ride. See Don't Move Firewood's frequently asked questions.

3) Take Care of Ash Trees on Your Property

If you have ash trees on your property, take care of them. EAB is attracted to trees that are stressed.

  • In the summertime, one of the main stresses on a tree is drought. Water and mulch young trees and mature trees.
  • Pruning cuts can send signals of stress to pests. If you have ash trees, avoid pruning them during the height of EAB activity (April through October).  

4) For Tree Care Providers

If you are a local tree care provider, become familiar with signs of EAB. Report sightings of EAB. Dispose of wood waste properly. Stay tuned for more information about wood waste policies in Portland.

5) Spread the Word!

Share this information with friends, family, and neighbors.

What Else is Being Done? 

Oregon Department of Forestry (ODF), Oregon Department of Agriculture, and community partners, including Portland, have been preparing for this event for years:

  • In 2009, The Oregon Invasive Species Council launched a statewide assessment of invasive species. The City developed the City of Portland Terrestrial and Aquatic Invasive Animal Assessment. This document details the City's specific role in invasive animal management.
  • In 2018, cooperating agencies developed Oregon’s EAB Readiness and Response Plan.  ODF provides ongoing education and guidance to cities and towns on best practice for slowing the spread of EAB.  
  • ODF has been collecting and saving Oregon ash seeds to preserve for future planting and also to test them for resistance to EAB.
  • ODF has been setting traps across the state to monitor EAB spread.
  • In 2019, City of Portland Urban Forestry removed ash species from Approved Street Tree Planting Lists.
  • In 2020, Portland's Bureau of Environmental Services surveyed more than 250 properties in the Johnson Creek and Columbia Slough watersheds. This survey helps the City better understand the potential impact of emerald ash borer on our region's urban forest.
  • In 2020, Portland City Council approved the Portland Invasive Species Strategy 2020–2030. This project charts a course for how the City and community address invasive species and their impacts. The strategy includes the emerald ash borer.
  • Portland has ongoing inventories of park trees and street trees. This data provides us with an understanding of where public ash trees are located and potential impact. Tree inventories are important tools for forest management. By planting a diverse species of trees and avoiding overrepresentation of any tree type, we aim to reduce susceptibility to pests and pathogens.
  • City of Portland Urban Forestry is developing an EAB Response Plan. Stay tuned for more information.

Additional Information

For Portland staff and community groups, contact weston.miller@portlandoregon.gov to order quad-fold brochures.