Spruce budworm

True fir forests east of the Cascade crest suffer most, though you may encounter this pest on landscape spruce and fir. Larvae feed on buds and growing tips, webbing the branch terminals together. Look for reddish-brown foliage by mid-summer on susceptible hosts like subalpine fir and grand fir. Damage accumulates over three to five years of consecutive defoliation, causing branch loss and crown thinning.

Most forest and shade-tree populations are naturally suppressed by parasitoid wasps and flies. For ornamentals, prune infested twigs and burn pruning material to eliminate pupae. Monitor trees after pruning to ensure recovery. Do not apply broad-spectrum pesticides, as these kill natural enemies.