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Importance - In eastern and southern states, oaks-particularly red oaks-are the most heavily damaged. Other hosts are green ash, black locust, elm, maple, willow, cottonwood, and sometimes fruit trees and ornamental shrubs. The damage-wormholes-causes unsightly scars on ornamental trees and degrade, estimated at 15 percent of the value of rough sawn lumber.
Identifying the Insect - Newly hatched larvae are 1/4 inch (6 mm) long and reddish pink. They gradually become greenish white and are 2 to 3 inches (50 to 75 mm) long at maturity. Brown pupal skins protruding from entrance holes are common in early summer. Adults are grayish, stout-bodied moths. The hindwing in the male has an orange spot.
Identifying the Injury - Earliest signs of attack are sap spots on the trunk. Later, frass is ejected from entrance holes. Burrows 2 inches (50 mm) in diameter under the bark, and galleries 1/2 inch (12 mm) in diameter and 5 to 8 inches (12 to 22 cm) long in the wood are typical. Galleries are open or loosely plugged with frass. Holes in lumber are dark stained.
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Larvae in oak.
Photo by William H. Hoffard, USDA Forest Service |
