There was no significant correlation between the diameter of the attacked trees and beetle attack density and there was only a weak correlation between the diameter of attacked trees and the number of emerged beetles per m2. Tree diameter may be a significant variable when individual stands are analyzed separately (Reid, 1963; Cole and Amman, 1969) but when data from several separate locations are incorporated into a single regression the strength of such correlations tend to be noticeably weaker (Berryman, 1976). The average attack density was relatively high, but not extreme (see Berryman et al. (1985) for a literature review). This suggests that the vigor of the sampled trees was relatively high (Raffa and Berryman, 1983).