Environmental Entomology (1984) 13, 522-530

Robert W. Campbell, Nilima Srivastava, Torolf R. Torgersen and Roy C. Beckwith (1984)
Patterns of occurrence of the western spruce budworm (Lepidoptera: Tortricidae): Larvae, pupae and pupal exuviae, and egg masses
Environmental Entomology 13 (2), 522-530
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 (<7-m), average (7- to 14-m), and tall (>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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Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Choristoneura freemani	Fir (Abies)	U.S.A. (NW)
	Choristoneura freemani	Douglas fir (Pseudotsuga menziesii)	U.S.A. (NW)