The emerald ash borer (Agrilus planipennis) is a destructive non‐native wood‐boring pest of ash trees (Fraxinus spp.). Native to Asia, the emerald ash borer beetle (EAB) was unknown in North America until its discovery in southeast Michigan in 2002. All native ash species are susceptible to attack. Ash trees with low population densities of EAB often have few or no external symptoms of infestation. EAB is a significant threat to urban, suburban, and rural forests as it kills both stressed and healthy ash trees. EAB is very aggressive and ash trees may die within two or three years after they become infested.