The emerald ash borer has a metallic, bright green body, a flat back and a rounded belly. It grows up to one-half inch in length.


Adult emerald ash borers eat ash tree leaves. Larvae feed on the nutrient-rich tissue just under the ash tree’s bark, forming S-shaped lines in the tree. This feeding process disrupts the trees’ ability to move food and water from its roots to its leaves, eventually killing the tree.


Because they are a non-native species, emerald borers have few natural predators in the Chesapeake Bay watershed. However, woodpeckers do prey on emerald ash borer larvae. Heavy woodpecker damage on an ash tree might be one sign that the tree has been infested.

Reproduction and Life Cycle

Between May and June, adults emerge from ash trees, leaving D-shaped exit holes in the trees. Females lay their eggs on ash tree bark between mid-May and mid-August. After the eggs hatch, larvae burrow under the bark. They feed on the tissue that carries food and water up and down the tree, which starves the tree to death. Larvae remain in the ash tree through the winter.

Did You Know?

  • The emerald ash borer was introduced to the Chesapeake Bay watershed in 2003 when a Michigan nursery shipped ash trees to Maryland.
  • The emerald ash borer has killed hundreds of millions of ash trees in North America.
  • The United States Department of Agriculture calls the emerald ash borer “the most destructive invasive forest insect ever to have invaded North America.”
  • The emerald ash borer has been reported in 35 states across the country, including all six Chesapeake Bay watershed states and Washington D.C.
  • There are things you can do to slow the spread of emerald ash borer:
    • Buy firewood where you burn it.
    • Familiarize yourself with quarantine information. Learn your state’s guidelines for handling emerald ash borers.
    • Do not plant ash trees. As the emerald ash borer is expanding its range across the country, planting alternative tree species is recommended for residential landscaping.
    • Learn the symptoms of infestation. Monitor your ash trees and look out for symptoms of emerald ash borer throughout the year.
    • Learn about treatment options. If you believe you have an emerald ash borer infestation and are not sure what to do next, check out this decision making guide for managing an infestation.

Sources and Additional Information