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EAB larvae is worm-like and live underneath the bark of ash trees. Photo by David Cappaert, Bugwood.org. -
Emerald ash borer larvae are creamy white with flattened, bell-shaped body segments. Photo by Toby Petrice, USDA Forest Service, Bugwood.org. -
Adult emerald ash borers are small, iridescent green beetles. Photo by David Cappaert, Bugwood.org. -
Adult emerald ash borers have a bright metallic red back (dorsal). Photo by David Cappaert, Bugwood.org. -
Emerald ash borer larvae carve S-shaped tunnels under the bark. Photo by Elizabeth McCarty, University of Georgia, Bugwood.org. -
Adult emerald ash borers are about 3/8 to 1/2 inch long and 1/8 inch wide, small enough to fit on a penny. Photo by Marianne Prue, Ohio DNR Division of Forestry, Bugwood.org.
At Risk
Emerald ash borer (EAB) kills ash trees. All ash trees (Fraxinus spp.) are susceptible to EAB. Millions of ash trees have already been killed across the United States and Canada.
Minnesota has the highest volume of ash trees in the United States, with nearly a billion forest and urban ash trees combined. The economic and environmental impacts of losing these trees are significant. The Minnesota Department of Agriculture (MDA) tracks the spread of EAB throughout the state and provides outreach materials, training, and management guidelines to affected businesses, communities, and land managers.
Distribution
Biology
In Minnesota, EAB completes one generation every one to two years.
Eggs are laid from mid-June through August. Female EAB deposit eggs individually on ash trees, between layers of outer bark and in cracks and crevices of the branches and trunk of the tree. Eggs typically hatch within two weeks, depending on temperature.
Ash trees are killed by the tunneling of EAB larvae beneath the tree's bark.
For a better understanding of the EAB life cycle, watch the video Cycle of Destruction.
Emerald ash borer flight season begins May 1
The MDA considers May 1 - September 30 to be the flight season for EAB. During this time, adult EAB beetles emerge from infested trees or wood and fly in search of new host trees.
EAB larvae complete development by pupating into adult beetles in the spring and early summer. However, this process occurs only when temperatures are sufficiently warm and requires a certain amount of accumulated heat - i.e., development time.
Identification
- Adults are small, metallic green, wood boring beetles about 3/8 to 1/2 inch long and 1/8 inch wide.
- Larvae are cream-colored with bell-shaped body segments. Larvae have two spine-like projections at the end of the body, called urogomphi, which are a defining characteristic. Size varies as they feed and grow beneath the ash tree's bark. The larvae create serpentine, or "S"-shaped, galleries under the bark. These galleries are a definitive sign of EAB when found in ash trees.
- Eggs and pupae are not commonly seen and are difficult to identify.
There are many insects in Minnesota that can be mistaken for EAB due to their size, shape, or metallic green color. Identification can be difficult if the insect is not found associated with an ash tree host. For more information, refer to Insects Commonly Confused with EAB reference sheet.
Regulatory Status: Regulated
Emerald ash borer is regulated at the state level. Ash material and hardwood firewood may not enter Minnesota from other states without proper certification.
Refer to the MDA's EAB Status Map for current quarantine boundaries.
Smarty Plants Podcast
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