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Western Spruce Budworm

Western spruce budworm larva
USDA Forest Service,
Western spruce budworm larva

The western spruce budworm, Choristoneura occidentalis Freeman, is the most widely distributed and destructive defoliator of coniferous forests in Western North America. It is one of nearly a dozen Choristoneura species, subspecies, or forms found throughout much of the United States and Canada. For more information on budworm biology, view Forest Insect & Disease Leaflet 53: Western Spruce Budworm.

Recently, tree-ring records were used to reconstruct spatial and temporal patterns of western spruce budworm outbreaks in mixed conifer forests of southern Colorado. Reconstructions of 11 host stands showed a regionally synchronous pattern of at least 14 outbreaks over the past 350 years. The outbreaks appear to be associated with periods of increased rainfall.

Find research publications about the western spruce budworm on Treesearch.