The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a destructive invasive insect native to eastern Asia that was accidentally introduced to North America in the Detroit, Michigan, area in the 1990s. Since then, EAB has caused almost 100% ash mortality in the areas it has spread in North America. Despite quarantine and control measures, EAB continues to spread across the US and parts of Canada. In June 2022, EAB was found in northwest Oregon near the Washington border. Oregon ash (Fraxinus latifolia), the Pacific Northwest s (PNW) only native ash species, is highly susceptible to EAB and could experience significant mortality throughout the region. Susceptible ash species native to Europe and eastern North America are commonly used as ornamentals in Washington cities, so urban and community forests could also be significantly impacted. This publication is intended for Extension professionals, Master Gardeners, public agency personnel, tree care professionals, and those who are interested in an in-depth review of the current state of knowledge about EAB and the implications for potential damage and mitigation strategies in Washington State. A separate publication, Managing Emerald Ash Borer in Washington State (Zobrist et al. 2023), is available for readers looking for a summary of EAB identification, distribution, impacts, and management recommendations
