United States Department of Agriculture
Animal and Plant Health Inspection Service
The emerald ash borer (Agrilus planipennis) is a destructive wood-boring pest of ash trees (Fraxinus spp.). Native to China, Mongolia, North Korea, South Korea, Japan, Taiwan, and the Russian Far East, the emerald ash borer beetle (EAB) was unknown in North America until its discovery in southeast Michigan in 2002. Today, EAB infestations have been detected in 25 states; Arkansas, Colorado, Connecticut, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin.
APHIS works with State cooperators to detect, control and prevent the human-assisted spread of the pest in order to safeguard America’s ash trees. Strategies to manage the pest focus on biological control, survey, regulatory activities, combined with public outreach and education initiatives to promote program support and compliance. APHIS continues work to identify effective tools to manage and control EAB populations.
Early in the EAB program, APHIS and the Forest Service (FS) initiated a search for potential biological control agents in The People’s Republic of China. Three potential biological control agents were identified; Spathius agrili, Tetrastichus planipennisi, and Oobius agrili. Since 2007, releases of these stingless wasps show promise as a long-term management strategy. Efforts are ongoing to find and evaluate additional biological control agents. More information about the EAB Biological Control Program is at: Emerald Ash Borer Biological Control Release and Recovery Guidelines.
EAB is a significant threat to our urban, suburban, and rural forests as it kills stressed and healthy ash trees. EAB is so aggressive that ash trees may die within two or three years after they become infested. Ash trees are as important ecologically as they are economically in the forests of the eastern United States. Ash trees fill gaps in forests and are highly desirable for urban tree planting. Ash wood is valued for flooring, furniture, sports equipment (e.g., baseball bats, hockey sticks, and oars), tool handles, and supplies for dairies, poultry operations, and beekeepers. Ash trees and ash wood are also significant to Native American cultures for traditional crafts and ceremonies.
During their larval stage, EAB feed under the bark of ash trees. This activity damages, and eventually kills, the trees. EAB adults mate shortly after emergence in the spring. Each female can lay 60-90 eggs in their lifetime and eggs typically hatch in 7-10 days. Minute larvae bore through the bark and feed on the nutrient-rich phloem. Larvae continue development into early fall. In the spring, EAB pupae start to transform into adults and in one to two weeks a new generation of EAB adult beetles emerge through D-shaped exit holes. Adults are most active on clear, calm days and are likely found on the warm, sunny sides of the trees. Adult EAB live two to three weeks.
In the United States, only ash trees are at risk for EAB. Ash trees are widespread in the United States and all 16 native ash species are susceptible to attack. Ash trees with low population densities of EAB often have few or no external symptoms of infestation. Symptoms of an infestation may include any or all of the following: dead branches near the top of a tree, leafy shoots sprouting from the trunk, bark splits exposing larval galleries, extensive woodpecker activity, and D-shaped exit holes.