Dryocoetes confusus (Scolytidae)

western balsam bark beetle


Adults:

Dryocetes confusus, the western balsam bark beetle, adults. Typical scolytid form with a length of from 3.4 to 4.3 mm. There is a dense brush of yellowish setae on the frons of the female, the frons of the male is only sparsely pubescent.


Larvae:

Dryocetes confusus, the western balsam bark beetle, larvae. Typical scolytid larvae in lower right. Elongate clerid bark beetle larva in top left.


Damage:

Dryocetes confusus, galleries. This insect is polygamous, usually 3 or 4 females for each male. Egg galleries radiate out from central nuptial galleries (similar to Ips spp. but only lightly scoring the wood). This insect kills trees in conjunction with a blue-staining fungus. In the ESSF, Pryocetes confusus sometimes kills the subalpine fir which has been weakened by its competition with Englemann spruce for light and moisture.


Principal Hosts:

Principally subalpine fir, but other Abies spp., Engelmann spruce and lodgepole pine are occasional hosts.

Economic Importance:

D. confusus is the most destructive species in its genus. May cause extensive damage throughout the range of its hosts in B.C. and the Western States southwards to Arizona and New Mexico.

References and Links:

FC: 380.

See HForest and JP17.

Additional Images:

Dryocetes galleries under subalpine fir bark Subalpine fir bark showing Dryocetes exit holes