Abstract
Samples drawn from sites in Washington, Oregon, Idaho, and Montana were used to determine intrastand patterns of occurrence of the western spruce budworm. The insects were counted on 45-cm terminal branch tips and whole branches taken from the upper, middle, and lower crowns of short ( 14-m) Douglas-fir and grand fir trees. Only average trees were sampled for instar IV. Across all crown strata, tree height classes, budworm life stages, and budworm densities studied, density on whole branches could be estimated from density on 45-cm terminal tips. For each budworm stage, consistent density relations were usually found among both live crown thirds and the three tree height classes. None of the relations above differed between the populations on Douglas-fir and grand fir.
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