The Early Intervention Strategy (EIS) in 2025 was successful and showed promising results for Maine’s forestlands. This EIS approach is going to be implemented again in 2026 to reduce spruce budworm populations that are near or above the action threshold to prevent significant tree damage and mortality.
Any updates on the EIS program in 2026 will be posted here.
Early Intervention Strategy 2026
Following the success of the Early Intervention Strategy (EIS) approach last year (Read more details on last’s years program “2025 Aerial Spray Program“), land managers in the Maine Budworm Response Coalition (MBRC) have opted to use the EIS approach again in 2026 to reduce elevated populations of spruce budworm and prevent an outbreak. This year, the Maine Forest Service is working with small landowners that are also participating in the EIS program.
The Maine Forest Service and the University of Maine Spruce Budworm Lab monitor spruce budworm (SBW) populations in Maine and the northeast to detect potential outbreaks before they happen. When SBW populations are elevated, natural enemies can no longer keep the SBW populations low and stable. Continued monitoring and L2 surveys during the Winter 2025-2026 season revealed roughly 83,000 acres of forestland with elevated populations of spruce budworm – a significant decrease compared to the hot spots present the year before.
Of the areas with elevated budworm populations, approximately 70,000 acres of forestland have been identified for potential treatments in late May and early June 2026 using targeted insecticides.
Which insecticides are going to be used in 2026?
The same insecticide products that were used last year will be used this year: tebufenozide (Mimic) or Btk (Bacillus thuringiensis kurstaki, Foray 76b). These insecticides will be applied by helicopter using modern technologies to ensure accurate applications. SBW populations may require additional treatment applications over the coming years to ensure the populations do not reach an outbreak level.
Applications from the helicopter will only be applied:
- On the tops of spruce-fir forest with spruce budworm populations that are near or above the action threshold
- No closer than 100 ft from lakes, streams, other bodies of water, and 1/4 mile from identified habitat of state-endangered and threatened butterflies
- In good water (no rain or high winds) to prevent drift or unintended applications
- Using reduced-risk insecticides (tebufenozide or Btk) that only affect larvae that eat treated foliage.
Where are insecticides going to be applied?
Spruce budworm populations are elevated in Northern Aroostook County, where the majority of the 2026 Early Intervention Strategy management will be taking place. Insecticide products are going to be applied to the tops of spruce and fir dominant stands that have elevated populations of spruce budworm.
A treatment map will be posted as soon as it is finalized.
When are treatment operations going to start?
The treatment window is approximately from May 26 to June 19, 2026. This timeframe is based on the expected development of the trees and the spruce budworm caterpillars. Treatments may be postponed depending on weather conditions. Additional treatment timing updates will be posted as the project progresses.
During active treatment applications, please adhere to any posted signs that may be in a treatment area or staff who may be blocking a road that leads to a treatment area.
Still have questions about spruce budworm or the EIS response?
We’re here to help. Multiple organizations are involved in the monitoring, research, and response to building spruce budworm populations. Find contacts on our contact page: