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Emerald Ash Borer


eastern ash borer - adultThe emerald ash borer is a small, green insect that threatens to kill a significant percentage of all ash trees in Fayette County. It was first identified in the United States in 2002. Since then, the emerald ash borer has been responsible for the death and/or decline of tens of millions of ash trees in the upper Midwest and Canada. The insect was found in Fayette County in 2010.

Specifically, the winged adult insect is metallic green in color, with a slender body that is a half-inch long and one-eighth inch wide.

life cycleAdult insects breed during the late spring and summer. Females lay their eggs on an ash tree’s bark. When the insects hatch 10 days later, the larvae tunnel under the bark and feed on the inner layers of the trees. The tunneling of larvae eventually cuts off the flow of water and other nutrients to the upper branches and canopy of the tree.

The larvae lay dormant during the winter and emerge from the trees in May.

exit holeThe adult borers leave a unique D-shaped exit hole in the tree. Then, the breeding cycle starts all over again.

The short-term results of the infestation are dieback of the upper canopy of the tree. There may be more woodpecker activity on infested trees. There may be wild, leafy shoots growing from the lower portion of the tree trunk. If pieces of tree bark split off of the infested tree, S-shaped tunnels will appear on the bare tree.

Left untreated, the entire tree dies within one to three years. Stressed trees will attract more adult beetles to infest nearby trees.

Quarantines and Controls

To prevent the additional artificial spread of the emerald ash borer, the state has issued a quarantine for 20 Kentucky counties – including Lexington - Fayette County – that prohibits the transportation of hardwood firewood, ash nursery stock, green ash lumber, the emerald ash borer insect or larvae or other materials that can spread the insect infestation.

It is especially important that firewood not be moved into or out of a county. This particularly affects campers who would bring firewood from home to a camp site or transport extra firewood from a camp site back home.

Prevention and Treatment

Research is ongoing for the best ash tree treatments – either to prevent an infestation or eliminate borers that have infested a tree. Pesticides can be applied as a “drench” around the base of the tree and have been somewhat effective in preventing and limiting borer infestations. Larger ash trees need to be treated with federally-approved insecticides by state-certified pesticide application companies. Treatments are generally applied once a year.

What Can You Do to Stop the Spread of EAB

  • Don’t Move Firewood – People unknowingly contribute to the spread of borers when they move firewood. Emerald ash borer larvae can survive hidden under the bark of firewood.
  • Identify Ash Trees in Your Yard – Ash trees are used extensively in residential and commercial landscaping. They represent two percent of all leaf cover in the United States and eight percent of known trees in Fayette County. Ash trees have oval-shaped leaves which grow opposite each other. The bark on some mature ash trees grows in a diamond-shaped pattern.  Click here to download a fact sheet on how to identify ash trees.
  • Visually Inspect Your Trees – Early detection is the key to mitigating infestation of the emerald ash borer. If a tree in your yard displays any of the signs or symptoms of emerald ash borer infestation, call the state agriculture department’s EAB hotline at 1-866-322-4512 or the Lexington forestry program staff at (859) 425-2558 for more information.
  • Spread the Word – Talk to your neighbors, friends, homeowners association and co-workers about the emerald ash borer and the damage it can do to trees. Tell them what to look for if a tree is infected.

Additional Resources

 How to reach us

Dial 3-1-1 or (859) 425-2255


Urban Forester
(859) 258-3404


Arborist Senior
(859) 258-3405


Last updated: 10/8/2013 10:01:19 AM