Columbian Timber Beetle
Corthylus columbianus

This beetle occurs over much of the East and south to Georgia and Arkansas. It attacks oaks (particularly red oaks), maples, birch, basswood, sycamore, yellow poplar, and elm, damaging the trunks of live trees of all sizes. Damaged wood cannot be used for veneer, cooperage, and furniture.

Identification:

Adults are black to reddish-brown cylindrical beetles about 1/5 inch (4 mm) long. The larvae are white, legless and C-shaped.

Injury:

Holes less than 1/10 inch (2 mm) in diameter are bored straight into the sapwood until the tunnel nears the heartwood, turning right or left. Damage is conspicuous in log ends. Streaks of stain originating from the tunnels are called flagworm defects.

Biology and History:

Adult beetles construct galleries. Eggs are laid in chambers along the main tunnel where the larvae live and develop. Larval food is a white fungus that grows on the gallery walls. There are two to three generations per year.