Eastern spruce budworm is a native caterpillar and is the most destructive pest of spruce-fir forests in eastern North America. Caterpillars prefer to feed on balsam fir and white spruce, but minimal feeding damage can occur on black spruce, tamarack, hemlock, and various pines.
While the northeastern United States and southeastern Canada experience major outbreaks every 30-40 years, some visible defoliation in most years has occurred in northeastern Minnesota since at least 1954. In Minnesota, outbreaks last about eight years before moving to a new area, and 30 to 40 years pass until spruce budworm returns. The majority of the current outbreak of spruce budworm is in northern St. Louis, Lake, and Cook counties. In 2023, the outbreak impacted just under 665,000 acres, the highest amount since 1961. Outbreak conditions eventually lead to widespread balsam fir and white spruce death.
Location
Eastern spruce budworm is found throughout northern and central Minnesota, wherever spruce and fir are present.
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Showing locations of eastern spruce budworm in northern Minnesota based on the percent of area affected.