Flatheaded appletree borer(Chrysobothris femorata) adult beetles are about a half-inch long, brown to gray, and flattened.
The body is blunt at the head and tapers to a rounded point at the posterior end. Wing covers appear to be finely corrugated.
Borers are about 1 inch long, legless, yellow-white, and slender except for a broad, flat enlargement of the thorax directly behind the head.
Borers leave a 3/16 of an inch D-shaped hole when emerging from a tree.
Host plants:
Flatheaded appletree borer has a very wide range of food plants including most deciduous such as young apples, crabapple, crapemyrtle, dogwoods, hawthorn, linden, maples and oak, fruit, forest and shade trees. Maples and apple are among the more common hosts.
Territory:
Eastern North America’s fruit-growing states and provinces
Damage caused by Flatheaded Appletree Borer:
The immature stage (a flatheaded borer) tunnels under the bark of trunks and larger branches, producing broad galleries that are tightly packed with fine sawdust frass. Areas of bark where injury has occurred often appear darkened, somewhat sunken and later may split above injuries. On young trees tunneling may girdle and kill the plant; tunnels are more restricted in area on established trees. Injuries are concentrated on the sunny side and most commonly occur on trees suffering sunscald, wounds or that suffer from drought stress.
Life history and Habits:
The larvae of the “flathead borer” are pale yellow, legless, and have a big thorax. Winter is spent under the bark as a larva. Adults may emerge as early as mid-spring, but late May and June are the busiest months. Adults are 1/2-inch long dark olive-gray to brown metallic wood borers. Within 8 to 16 days, the eggs hatch, and the larvae gnaw through the bottom of the egg to begin tunnelling into the tree. Larval development can be quick and gallery creation extensive in low vigour trees. In trees with great vigour, development is slowed and tunnelling is inhibited. They eat for several months before going dormant throughout the winter months. There is one generation annually.
