Emerald Ash Borer Found in Portland

Emerald ash borer (EAB), the tiny green invasive insect that infests ash trees, has been discovered in Portland. Since it was first detected in Michigan in 2002, EAB has killed millions of ash trees across the country. The discovery in Portland, while unwelcome, was not unexpected and follows the predicted spread of the beetle.

First found in Oregon in 2022 at a school in Forest Grove, this summer the insect showed up in traps in six new areas, including at a trap in the Hazelwood neighborhood in southeast Portland at the David Douglas Aquatics Center. Green ash trees at that site have thin canopies, which can be a symptom of EAB infestation, and one tree also had serpentine gallery marks under the bark, a telltale sign of this insect.

How is the City Responding?

The City of Portland has been preparing for EAB's arrival for years. It removed ash trees from its list of approved street treesin 2019 and released a comprehensive response planfor dealing with EAB earlier this summer. This plan, among other things, involves the treatment of healthy park trees, the proactive removal of ash trees in poor condition, and reducing or removing barriers for the public in managing their ash trees.

What you can do:

There is still a lot that Portlanders can do to slow the spread of the bug across the city.

Learn to identify ash treesand common signs and symptoms of EAB. If you see an ash tree that looks like it could be infested with EAB, you should report it to the Oregon Invasive Species Council Hotline, with a description and clear photos.

Residents with ash street trees or private trees can use insecticides to protect their trees against infestation. When applied by a licensed pesticide applicator, these treatments can be up to 95% effective. Without treatment, ash trees will eventually become infested and need to be replaced. Proactively removing ash trees before they are infested with EAB and replacing them with a suitable species for the site is also an option. A local tree care providercan help you assess your trees and determine if treatment or removal and replacement is right for you. All street trees and some private trees require a permit from the City.

Read moreabout how the City is responding to EAB, and what you can do to slow the spread of this invasive pest.