SPRUCE BEETLE BROOD PRODUCTION IN LOGGING SLASH AND WINO-THROWN TREES IN BRITISH COLUMBIA BY

In British Columbia, the spruce beetle attacks and kills many mature spruce, during periodic outbreaks. The beetle usually breeds in logging slash and wind-thrown t.rees I but when populations increase to epidemic levels, standing living trees are [requelltly attacked and killed. A large increase in the beetle population depends on the avail-ability of large amounts of suitable host material. In the Prince George region, fresh logging slash and recently wind-thrown trees in the forest boundaries of new clear-cut areas are usually abundant where spruce stands are being harvested. This material is attacked by the beetle, and broods develop 1n the selected shaded parts of slash and in all bark of wind-thrown trees in forest shade. In exposed slash or trees, solar heat. or winter cold can be lethal to the broods under the bark. The broods usually require two seasons to mature but following a warm summer, more than half the larvae may complete development uy the first autumn. Survival through the second year is poor in slash but generally good in shaded wind-thrown trees. Because such trees are the. principal sources of beetle population increase, their removal, within a year, from logging boundaries and road edges is strongly recommended