Emerald Ash Borer killing ash trees in north Alabama
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Adult EAB emerging from the stump of a recently cut ash tree.
Galleries beneath the bark made by EAB larvae
Special to the News
After investigating reports of dying ash trees in Jackson and Madison counties in north Alabama, the Alabama Forestry Commission, or AFC, has identified the non-native Emerald Ash Borer (EAB) as the culprit.
This is the first confirmed observation of the pest in those counties. Previously, the agency had documented EAB in Etowah, Calhoun, St. Clair, Talladega, and Shelby counties.
“Emerald ash borer damage usually begins at the top of the crowns of ash trees and proceeds downward,” said AFC Forest Health Coordinator Drew Metzler. “Many landowners do not realize there is a problem until it is too late, and the larvae of the EAB have essentially girdled the tree down to the stump.”
While adult emerald ash borer causes minor damage to host trees, newly hatched larvae are the most destructive by boring into the phloem and cambium layers of the trees. They feed and create winding galleries underneath the bark, preventing transportation of water and nutrients. Once the larvae reach a mature size, they tunnel into the outer sapwood.
Emerald ash borer (Agrilus planipennis) is a non-native wood borer from Asia that was first detected in Michigan in 2002. It most likely came into the U.S. on untreated wood packing material from China. The insect will attack all native species of ash (Fraxinus genus).
The adult emerald ash borer is metallic green and approximately half an inch long. The bullet-shaped body is narrow and elongated. The head is somewhat flat with large, black eyes and two short antennae. The creamy white larvae are 1 to 1.5 inches long. Eggs of the emerald ash borer turn yellowish-brown right before they hatch.
Adult EAB emerge from pupation near the surface of the tree from April to early July, with peak emergence occurring in June. When adult borers emerge, they create D-shaped exit holes approximately three-sixteenths of an inch in diameter in the infested trunk and branches.
For the next two weeks, the adults feed on ash foliage to complete maturation. Once the adults reach this developmental stage, mating occurs. From May to August, each female adult borer lays approximately 70 eggs – in some cases, as many as 300 – in bark crevices or between bark layers. Adult ash borers may continue to be active until October.
Metzler noted that there are treatments that landowners can conduct to protect ash trees from EAB damage, especially if caught early. Infested ash trees that are cut down should preferably be burned or destroyed on-site to slow down the dispersal of the insect.
For more information or advice, contact your county forester or local AFC office. The Alabama Forestry Commission is the state agency committed to protecting Alabama’s invaluable forest assets.
