Photo: Federico Bottos on Unsplash.com

By Laura Durenberger-Grunow - Boreal Community Media - January 20, 2026

The Minnesota Department of Natural Resources (DNR) recently released its 2025 Forest Health Annual Report, which summarizes aerial survey results, pest and disease trends, and identifies potential hazards from the year. In 2024, record-breaking defoliation, mainly due to the ongoing spruce budworm outbreak, was the main impact, while the 2025 report shows how the damage has increased regional wildfire risk, particularly in Cook and Lake counties.

Spruce Budworm

In Cook County and elsewhere throughout NE Minnesota, the spruce budworm outbreak continued in 2025. The native caterpillar, which primarily eats balsam fir and white spruce needles, has been active in this area for several years. According to the DNR, the outbreak is following a "predictable yet damaging path," essentially "eating its way" through the dense conifer stands of the Arrowhead.

The DNR reported that aerial surveys in 2025 mapped over 180,000 acres of forest with defoliation and mortality across the Arrowhead, with over 80 percent of that damage within Lake and Cook counties. This is a decline from the 712,000 acres recorded in 2024; however, the DNR added that this is likely an underestimate. Smoke from Canadian wildfires delayed or challenged many 2025 survey flights, making it difficult for researchers to capture the full extent of the infestation. According to the report, "The true impact is suspected to be similar to that of 2024 based on field work and reports from field staff."

Image: MN DNR 

Local officials have responded to these impacts through multiple public outreach efforts. In mid-2025, University of Minnesota Extension and Cook County offices released a spruce budworm guide for local landowners to help them identify symptoms and determine when and how to take action. This was followed by a spruce budworm symposium held in November, with the goal to educate community members on management strategies such as thinning dense stands and removing "ladder fuels" that increase wildfire hazards.

According to the DNR, spruce budworm "damage is expected to continue for the next 5 to 7 years in Lake and Cook counties."

Emerald Ash Borer

In addition to native pests, the invasive emerald ash borer (EAB) was confirmed to have spread to new areas in Lake County last year. First discovered in the county in 2022 along the Superior Hiking Trail in Two Harbors, the new discovery was located around Silver Bay. EAB has now been confirmed in 59 Minnesota counties and in Thunder Bay, Canada. 

In response to the continued spread throughout NE Minnesota, Cook County officials hosted local educational events to help community members identify potential signs of EAB, as well as a family-friendly informational event at Voyageur Brewing. 

Eastern Larch Beetle 

The eastern larch beetle, a small native insect that lives under the bark of tamarack trees, has caused a decline across Minnesota for over two decades. Typically, the beetle is attracted to stressed trees; however, according to the MN DNR, the insect population has expanded due to climate-driven factors such as longer growing seasons and increased reproductive rates, allowing them to overwhelm healthy, mature stands. Smaller tamarack trees remain "resistant" to the beetle, and many affected areas are showing signs of "natural regeneration." The DNR stated that since 2001, this outbreak has impacted more than 1.2 million acres of tamarack forest.

In 2025, the DNR mapped nearly 299,000 acres of damage, marking the highest level of activity since 2022. A notable portion of this damage occurred in new areas, particularly in Koochiching County. While the outbreak may be reaching its peak in terms of new annual expansion, it is expected to persist for several more years, according to the DNR. 

Management efforts continue through sustainable timber salvage and reforestation, the organization said. 

Wildfire

In May 2025, two major wildfires, the Camp House and Jenkins Creek fires, burned approximately 28,000 acres. As shared in the DNR 2025 forest health report, the fire was human-caused; however, it was fueled by an "abundance of standing dead wood left behind by previous years of budworm damage." The DNR stated that wildfire risk peaks roughly 5 to 8 years after trees die, a timeframe that matches the current peak in tree die-offs across the Arrowhead.

Future management efforts in the region remain focused on long-term forest health, the DNR said. Partnering organizations such as the Superior National Forest and the North Shore Forest Collaborative are actively working to remove dead balsam fir and, along with others, including The Nature Conservancy and Lutsen-based Let's Plant Trees, replant diverse, more fire-resistant species (ex, white pine). According to the DNR, diversifying the forest composition is the most effective way to reduce the impact of future spruce budworm cycles and protect the region from catastrophic wildfires.

To read the full report, click here.