6 Things to Know about the emerald ash borer

Local News

(Photo via ProtectTnForests.org)

KNOXVILLE, Tenn. (WATE) — Much of the recent bug news has been focused on cicadas, but many Ash tree owners should know about another bug, the emerald ash borer.

Emerald Ash Borer Awareness Week is May 23-29.

What does the emerald ash borer look like

(Photo via ProtectTnForests.org)

The adult emerald ash borer are bronze, golden, or reddish-green, about 1/2 inch long and 1/8 inch wide. They have darker metallic green wings with a metallic purple-red underside. Adults can be seen from June to August.

The larvae are 1 to 1.2 inches long, and they are white or cream-colored. They will make S-shaped galleries under the bark of the ash tree that can be seen year-round.

Largest size class collected in early September, some individuals appeared to have completed feeding. Maybury State Park, Michigan; August 30, 2002

History of the EAB

The emerald ash borer (Agrilus planipennis) is originally from Asia but it was first found in the United States in 2002 in Michigan. It has since caused widespread tree mortality and decline in ash trees in 18 states including Tennessee, and Kentucky.

The insect was identified in Tennessee in July 2010 at a Knox County truck stop on Interstate 40.

(Photo via ProtectTnForests.org) Knox County, July 2021
(Photo via ProtectTnForests.org) Knox County, August 2010

As of July 2020, wood from 65 counties in the eastern half of the state are quarantined due to the pest.

Signs of an infection

  • The leaves begin to wilt and branches die leaving a sparse canopy.
  • D-shaped holes appear in the bark where the adult beetles emerged.
  • It takes 1-3 years of infestation before an ash tree begins to show signs of mortality or decline.
(Photo via ProtectTnForests.org) Knox County, August 2010

Why the tree dies

Trees die as the larva feeds on the tissue between the sapwood and the bark disrupting the transportation of nutrients and water. This eventually causes the branches to die, followed by the entire tree.

Small trees will likely die within one to two years of becoming infested, for larger trees to will can take three to four. If caught early, infested ash trees can be treated and protected, but if not treated, the tree will die.

How to keep Ash trees safe

ISA-certified arborists can be hired to treat large healthy trees and can effectively keep them alive for years despite infestations; however, dead trees do need to be removed.

Smaller healthy trees can be treated by the homeowner with over-the-counter insecticides labeled specifically for the borer. Water, mulching and pruning the trees also help keep them healthy.

As the bug is mainly transported by humans, people are asked to be aware when moving firewood and other ash products. Protect TN Forests suggest not moving Ash Tree firewood whenever possible.

Learn More

Protecttnforests.org also has more information about and other destructive forest pests in Tennessee.

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