HOSTS: Deciduous fruit, forest, and shade trees. Ash, Maple and apple are the most common hosts. Arborvitae are attacked by a related species.

DESCRIPTION: Larvae are pale yellow and legless with an enlarged, flattened thorax. Adults are dark olive-gray brown metallic wood boring beetles about ½” long.

DAMAGE: Immature stages tunnel under the bark of trunks and larger branches producing a fine sawdust frass. Tunneling may girdle and kill young trees. Injuries are concentrated on the sunny side of trees. Beetles most commonly attack trees suffering sunscald, wounds or drought stress.

LIFE CYCLE: Larvae over winter in host plants. In spring, they pupate and bore holes in the host tree. Adults emerge in late spring and lay eggs which hatch into larvae in late summer.

CONTROLS:

Cultural: Attacks by flatheaded borers are concentrated around wounds, cankered areas, and on drought-stressed trees. Healthy trees are less attractive to egg laying females. Larvae are often killed by the trees defense system which oozes sap. Dying trees and newly cut wood should not be kept near susceptible trees since large numbers of borers can develop in these materials. Once borers are present in the trunk, digging them out in late summer or early fall is the only control. This is difficult to do without causing additional injury.

Chemical: Spinosad can be applied in late spring to tree trunks.