Columbian Timber Beetle
Corthylus columbianus (Hopkins)
J. D. Solomon, F. I. McCracken, R. L. Anderson, R. Lewis, Jr., F.L. Oliveria, T.H. Filer, and P.J. Barry
Importance – This beetle occurs over much of the East and attacks the white oaks and, to a lesser extent, the red oaks. It attacks the trunks of live trees of all sizes. Damaged wood is degraded for such uses as veneer, cooperage, and furniture.
Identifying the Insect – Adults are black to reddish-brown, cylindrical beetles about .2 inch (4 mm) long. The larvae are white, legless and C-shaped.
Identifying the Injury – Hole less than .1 inch (1 to 2 mm) in diameter, are bored straight into the sapwood until the tunnel nears the heartwood, then it turns right or left. Damage is conspicuous in log ends. Streaks of stain originating from the tunnels are known as flagworm defects.
Biology – 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.
Control – There is no apparent relationship between tree vigor and susceptibility. No natural enemies have been found. Protection of veneer-quality trees with insecticides seems possible.
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