Tetropium velutinum (Cerambycidae)

the western larch borer


Adults:

Pinned adult specimens of Tetropium velutinum, the western larch borer. Elongate, velvety brown beetles about 12 mm long. Eyes divided in two parts. Long antennae give this family of beetles the "longhorned" beetle common name.


Larvae:

White, elongate, elyptical in cross-section. Narrow thorax. Small thoracic legs present. Segments distinct. Body not strongly tapered.

Damage:

Common in fire killed timber, cold deck piles left over summer, drought weakened and insect defoliated trees. Larva is a shallow sapwood borer and bark miner. The larva do enter the wood to pupate. The holes left in the wood are elliptical in cross-section and adult exist holes are circular.

Principal Hosts:

Western larch, Douglas-fir and western hemlock are the preferred hosts. Species of Abies, Pinus and Picea are recorded hosts.

Economic Importance:

During the drought of the 1930's this species caused extensive deterioration of larch stands in N.W. Washington.

References and Links:

FC: 294.