Western Spruce Budworm
Choristoneura freemani
HOST Douglas-fir, fir, spruce, larch
DAMAGE/SYMPTOMS On the needles, insect excrement and webbing are present. The caterpillars can cause defoliation, deformation of the needles, and chewing damage.
LIFE CYCLE The caterpillars emerge in the spring and begin feeding. They pupate and reach adulthood in July. The females lay eggs, which hatch in about 10 days. In late July, young caterpillars create a cocoon-like structure to spend the rest of the season.
MANAGEMENT Beneficial predators can help to control populations of the budworms. Monitoring for the caterpillars allows for properly timed chemical applications. Several contact insecticides, including the bacterium Bacillus thuringiensis variety kurstaki, are available for caterpillar control.
A Western spruce budworm damage. B Western spruce budworm pupa and damage. C Western spruce budworm caterpillar.