Spatial Attack Pattern of a Western Washington Douglas-Fir Beetle Population

Spatial attack pattern of the Douglasfir beetle, Dendroctonus pseudotsugae Hopkins, was investigated using R, the distance to the nearest neighbor, and I δ , Morisita's index of dispersion. The attack pattern on 15 trees was shown to be uniform, and although the mechanisms directly controlling attack spacing were not investigated, a hypothesis involving bark distribution, sonic interaction, and short-range repellent pheromones is presented. Forest Sci. 22: 100-102.