Spruce Budworm Outbreak in Northern Maine Sparks Alarm

After nearly two decades of sporadic incursions from Quebec, a more severe spruce budworm outbreak has been detected in Maine’s Aroostook County, the Portland Press Herald reported (11-18-24). State entomologist Michael Parisio identified a 3,000-acre swath of partially defoliated spruce-fir forest, raising fears of a repeat of the devastating infestation that ravaged the state 50 years ago.

The patch of defoliated trees near Little East Lake just east of the Canadian border was a sign the native budworm population had grown so large that its consumption of fir and spruce needles was visible from a thousand feet above the forest.

“We’ve had a few scares here and there, but 3,000 acres, that’s significant damage,” Parisio told the Press Herald. “That is a hot spot that won’t go away in a year. All evidence suggests it will persist and expand. We knew it would get here eventually, but knowing doesn’t make what’s going to happen any easier.”

University of Maine modeling shows that more than 178,000 acres are on the verge of defoliation when budworm larvae emerge from their already-hung cocoons next spring hungry for the buds that grow at the end of spruce and fir trees in Maine, the most heavily forested state in the country.

The last outbreak lasted from 1967 to 1993, covering 136 million acres across eastern Canada and Maine. It stripped the needles from fir and spruce trees across most of northern Maine, killing 7 million acres of trees and costing the state’s forest economy hundreds of millions of dollars.

Maine hopes to avoid a repeat of that ruin through an aggressive whack-a-mole management approach, the Press Herald reported. The state has expanded its ability to look for cocooning budworms before they emerge in the spring and begin to feed, giving landowners time to spray the infested stands with just enough pesticide to return a hot spot to non-threatening levels that can be kept in check by weather and natural predators, like birds.

New Brunswick has used this early intervention strategy to stop Quebec-based budworms at its borders. “Think of it like whack-a-mole,” said Angela Mech, a University of Maine associate professor of forest entomology. “We try to hit it as soon as you see an uptick in the population, not after it explodes. That way we can contain it before it causes significant defoliation and creates a landscape of dead trees.”

To do this, Maine opened the country’s only spruce budworm lab, where limbs from hundreds of areas across Maine are taken each winter and inspected for signs of overwintering budworms: cocoons. Now dormant, those cocooned larvae emerge in the spring with a hankering for fir-spruce buds.