COURTESY OF MAINE FOREST SERVICE FOREST HEALTH & MONITORING
Recently, spruce budworm has been turning heads in Northern Aroostook County. In June 2024, the caterpillars’ extensive feeding damage caused reddish-brown hues to develop on spruce and fir trees. Maine Forest Service surveys revealed 3,400 acres of damage from the caterpillars visible from the air. Then, 2024 branch sampling of the overwintering budworm estimated roughly 300,000 acres with building populations.
Spruce budworm is not new to Maine’s forests; it is a native species that is always present, but it can occasionally outbreak and cause significant tree mortality. In areas with building outbreak populations, their natural enemies (predators, pathogens, and weather) are no longer able to keep budworm populations low and stable.
During the last major outbreak in the 1970s, Maine used a foliage-protection strategy that focused on insecticide treatments to keep valuable trees alive during an active outbreak. Using that approach, roughly seven million acres of spruce and fir trees were still damaged or killed. This caused waves of change in Maine including diminished water quality and disruptions to the natural resources and their dependent communities for the decades that followed.
The difference today is the development and success of a new management approach: Early Intervention Strategy (EIS). Initially developed and tested in Atlantic Canada, EIS aims to reduce spruce budworm populations early – when they are still low – but on the rise instead of waiting until populations have exploded to help trees.
The goal of EIS is not to eliminate spruce budworm, but rather to knock down populations in areas where they are poised to overwhelm control by their natural enemies. This new approach to treatment timing has drastically reduced tree damage and the size of the areas needing to be managed.
Coordinated Response in 2025
In response to the elevated populations of spruce budworm, timberland owners and managers in Maine formed the Maine Budworm Response Coalition (MBRC). Together with numerous agencies and organizations, including the Maine Forest Service and the Spruce Budworm Task Force, a plan to manage spruce budworm was crafted.
After months of monitoring, planning, public communication, outreach, and a helpful stretch of good weather and bud growth, the MBRC coordinated aerial treatments to curb growing spruce budworm populations in May 2025. Precise application technology and target-specific insecticides ensured efficient applications, and the response was considered an operational success: budworms that died because they ate the insecticide were present in treated stands along with abundant evidence of budworm death from natural enemies, including insects. Aerial surveys in July 2025 confirmed healthy and green spruce-fir forests that had been treated earlier in the season in contrast to untreated adjoining areas.
Looking Ahead to 2026
As expected, budworm populations persist above treatment thresholds in some parts of the state, particularly in areas not treated in 2025. In some cases, spruce budworm populations in treated areas may also increase from the current outbreak in Canada extending into Maine. Sampling throughout this fall will help pinpoint those hot spots and provide a first look at what areas may be eligible for treatment in 2026 to reduce spruce budworm impacts. Keeping our forests healthy is a shared effort. Landowners with smaller woodlands (~20-2000 acres) are part of an EIS solution.
We anticipate a program to subsidize treatment costs on smaller woodlands in Northern Aroostook County in 2026.* If you are interested in learning more about participating in the spruce budworm response in 2026, please fill out the interest form at maine.gov/sbw or contact the Maine Forest Service for assistance at (207) 287-2431 or [email protected].
*Note: We cannot guarantee that lands of all interested owners will be eligible for treatment. Spruce budworm populations, funding, sensitive areas, forest composition, interest and other factors will all drive the eligibility of specific areas for enrollment.
