Tiny but destructive, the emerald ash borer (EAB) is an invasive beetle that has killed millions of ash trees across North America. In some cases, infested regions have lost nearly 100% of their ash trees to this pest. Though EAB has not yet been found in California, it was detected on the West Coast for the first time in 2022 near Portland, Oregon. Since then, it has spread to four counties in Oregon. California is home to several tree species susceptible to EAB, including native Oregon ash and Modesto ash. EAB can also reproduce on olive trees, which are abundant in California.
During Emerald Ash Borer Awareness Week (May 18-24, 2025) we encourage you to protect California’s forests by learning how to identify and prevent the spread of this invasive pest.
- Attend a free webinar. Four webinars will be offered during Emerald Ash Borer Awareness Week. Tune in to hear from experts on this pest and its damage, spread, and management.
- Learn how to identify EAB. Visit the California Department of Food and Agriculture (CDFA) webpage about EAB and read UC IPM’s Invasive Pest Spotlight: Emerald Ash Borer.
- Do not move firewood! EAB and many other harmful invasive pests hitchhike on firewood. Help protect our forests by collecting or buying firewood as close as possible to where you plan to use it. Learn more at firewood.ca.gov.
- Identify susceptible trees in your yard and monitor them for signs of EAB. If you suspect an EAB infestation, report it to your local county agricultural commissioner or to CDFA. Be aware that there are other wood-boring insects in California that might be mistaken for EAB and can cause similar kinds of damage.
Consider planting alternatives to ash trees. If you are planting a tree, consider choosing a species that isn’t susceptible to EAB.
An adult emerald ash borer on a leaf with feeding damage. Credit: Debbie Miller, USDA Forest Service, Bugwood.org.