Western Spruce Budworm

Western spruce budworm larva

What You Need to Know

The western spruce budworm is a drab, inoffensive-looking caterpillar--and the worst defoliator of coniferous forests in the American West. It attacks spruces and other common conifers, eating the needles, flowers, and cones.

Are My Woods at Risk?

Western spruce budworms attack more than just spruce. In addition to blue, Engelmann, and white spruce, they also feed on Douglas-fir, grand fir, white fir, subalpine fir, corkbar fir, and western larch. They sometimes also feed on Pacific silver fir, mountain hemlock, western hemlock, lodgepole pine, ponderosa pine, western white pine, limber pine, and whitebark pine.

The western spruce budworm has been found in every state from the Rockies to the west coast. It is most widespread in the Rockies and the Pacific Northwest. This map shows the geographic distribution of western spruce budworm in 2011.

With the right information, you can manage your woods well even during an outbreak. Start by learning a little about western spruce budworm, or jump to steps for damage control or prevention. And remember, help is always available.

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