Spruce Budworm Infestation Fuels Worsening Wildfires in Northern Minnesota.

Wildfires are currently tearing through vast stretches of Northern Minnesota, consuming thousands of acres, damaging property, and forcing evacuations. While the Camp House, Jenkins Creek, and Munger Shaw fires remain uncontained, experts are pointing to a tiny but destructive contributor: the spruce budworm.

These caterpillars have plagued Minnesota’s forests for decades, feeding on the needles of balsam fir and spruce trees until the trees die. Their impact, however, extends far beyond deforestation. By killing trees and leaving behind dry, dead wood, spruce budworms significantly increase the likelihood and intensity of wildfires.

“The budworm’s biggest influence is that it promotes dense stands of fire-prone balsam fir,” said Mike Reinikainen, a silviculture expert with the Minnesota Department of Natural Resources (DNR). The situation echoes past events, including the 2021 Greenwood Fire near Isabella, where budworm-damaged trees contributed to the fire’s severity.

Spruce budworms begin life as larvae that feed heavily on tree foliage before maturing into moths. Each moth lays up to ten egg masses before dying within the year. While they serve as a food source for birds such as the Cape May warbler and purple finch, their role in weakening forest health is significant. Their destruction often clears the way for balsam fir regeneration, further perpetuating the cycle.

According to the DNR’s 2024 Forest Health Annual Report, human efforts to suppress natural fires may have unintentionally fueled the problem. Fire suppression allows spruce and fir trees to grow older and denser, creating more food and habitat for the budworms. “Balsam fir acts like a ladder,” explained Sarah Waddle of the University of Minnesota Extension, “helping flames climb from ground level into the forest canopy.”

The current outbreak, which began around 2020, has impacted over 700,000 acres—mostly in Lake, Cook, and St. Louis counties. This marks the most widespread infestation since 1961, with more than 90% of recent damage occurring in those areas.

Spruce budworm outbreaks occur every 25 to 40 years and can persist for up to ten years. The species has been native to Minnesota for centuries, with monitoring efforts in place since 1954.

To reduce risk, Waddle recommends removing infected trees to allow for decomposition and wildlife shelter. She also suggests planting a greater variety of tree species and consulting local conservation or DNR foresters for guidance.

Source:https://phys.org/news/2025-05-worm-perpetuated-wildfires-northern-minnesota.html

This is non-financial/medical advice and made using AI so could be wrong.