The boles of 71 mature ponderosa pine trees killed by Dendroctonus brevicomis LeConte (Coleoptera: Scolytidae) were analyzed to determine the distribution of the attacks by endemic populations of this bark beetle and those of several phloem -feeding associates. The longitudinal -circumferential distribution of the attacks fitted dia- grammatically into four distinguishable bole infestation patterns. The characteristics of the patterns and similarities with comparable ‍?attacks of D. brevicomis in northeastern California are discussed.

Two empirical methods for rating susceptibility of mountain pine beetle attack in ponderosa pine were evaluated. The methods were compared to stand data modeled to objectively rate each sampled stand for susceptibly to bark-beetle attack. Data on bark-beetle attacks, from a survey of 45 sites throughout the Colorado Plateau, were modeled using logistic regression to estimate the probability of attack on individual trees from tree and stand variables. The logistic model allowed flexibility to easily scale results up to a stand level for comparison to the empirical methods. The empirical method, developed by Munson and Anhold, most closely correlated to the logistic regression results. However, the Munson/Anhold method rated all 45 study sites as either moderately or highly susceptible to bark-beetle attack, which raises concern about its lack of sensitivity. Future work on evaluating risk of bark-beetle impact should consider more than stand characteristics.