Distribution of attacks and egg galleries by the spruce beetle around the hole of windthrown trees


  • L. Safranyik Pacific Forestry Centre 506 West Burnside Road Victoria, BC V8Z 1M5


Spruce beetle, attacks, circular distribution, survival, sampling


The distribution of attack density and egg gallery length by the spruce beetle around the bole of windthrown spruce trees was investigated in central British Columbia. In windthrown trees that are oriented north-south or east-west, the circular distributions of both attack density and egg gallery length were significantly different from the uniform distribution. The mean directions for the center of n1ass of the distributions suggest an evolved preference by the spruce beetle for establishing broods relative to habitat quality. The preferred habitats for brood establishment were the shaded bottoms and lower sides of windthrown trees. This finding is consistent with the hypothesis that attack preference is a function of solar insulation during the attack period.


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