Christmas tree farmers in Aroostook County knew trouble was ahead when swarms of spruce budworm moths, some massive enough to be visible on radar, started riding wind currents from Canada into northern Maine in 2019.
Within a couple years, Ben Voisine, manager of Allagash View Farms in New Canada, noticed the insects defoliating his trees. An outbreak that started more than a decade earlier in Quebec had finally reached his trees.
“There were too many holes and gaps in them to be salable as Christmas trees,” Voisine said. “It’s been kind of a constant battle for our farm.”
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Insect specialists say the outbreak, if left unchecked, could last another 10 years and cost Maine’s timber industry $800 million a year. This time, instead of the broad pesticide spraying that failed to stop the last major outbreak, the state is targeting only the most heavily infested areas, and only when the insects are at their most vulnerable stage.
Spruce budworm is considered one of the biggest threats to Maine’s balsam fir and white spruce trees, which make up more than a third of the state’s forestland. The $800 million-a-year projection, along with an estimated 300 million-split-piece annual reduction in firewood harvest, comes from the Forest Resources Association.
The last outbreak damaged more than half a million acres of northern Maine trees. But the early results of the more targeted effort, which began last year, are promising.
In the first year, some 240,000 acres of forest in northern Maine were treated, and follow-up monitoring found 95% fewer pests in the treated area, according to the University of Maine. About 70,000 acres more were treated in June, including commercial timberlands, state lands and 127 private woodlots. Researchers won’t know the results of that spraying until the late winter of next year.
Vernon Labbe, owner of Labbe Tree Farm in Frenchville, about 12 miles east of Fort Kent, signed up for the state program and said the aerial spraying kept tree damage at his farm to a minimum. Denser infestations were west of his farm, including at Allagash View Farms, where Voisine had not signed up in time for the program and sprayed his own land. Voisine lost about $600,000 worth of trees that otherwise would have been ready for harvest in the next year or two.
Scientists at the Maine Forest Service, Spruce Budworm Task Force and the University of Maine devised the early intervention strategy after the last major outbreak, which started in 1967 and lasted 26 years, peaking in the 1970s and 1980s.
It killed or permanently damaged spruce and fir trees on more than 667,000 acres in northern Maine and cost the timber industry hundreds of millions of dollars, the Maine Spruce Budworm Task Force estimated. The state still is recovering from the damage. Fir trees grow about one to two feet per year.
The insects are native to Maine and typically are controlled by predators including birds, but their numbers boom in 30-year cycles for reasons still unknown, scientists said.
“It’s crazy to think that just one small insect can have such a big impact on the state,” said Angela Mech, a University of Maine forest entomologist working on the early intervention strategy.
The spruce budworm starts as a dark brown caterpillar with light-colored spots on its back and a dark, shiny head, then grows into a half-inch-long moth with mottled brown and gray wings. Mature budworm caterpillars munch on the buds of their favorite food, balsam fir and white spruce trees. Those buds normally open into needles in the spring, but when the insects eat the buds and needles, the trees cannot convert sunlight into food and they die.
During the last major outbreak, more than a million acres of northern woods were sprayed by air using pesticides, but more than 84% of balsam fir trees died anyway, leaving behind large swaths of gray and red timber that had been slowly eaten to death. The unsuccessful aerial spraying effort also relied on synthetic chemical insecticides that killed beneficial insects such as pollinating adult bees and butterflies in their caterpillar stage.
When the Canadian outbreak that has been creeping toward Maine started in 2006, tree experts in the state knew they needed a new strategy to protect the forest. They accelerated their efforts in 2013, when spruce budworm populations began building up in eastern Quebec.
“They were getting towards areas where they could impact Maine,” said state entomologist Allison Kanoti, who also directs forest health and monitoring at the Maine Forest Service. “The goal is to prevent a repeat of the 1970s and 1980s outbreaks.”
An aerial survey in July 2024 confirmed that 3,000 acres of Maine’s forest near Little East Lake were already denuded by spruce budworm, according to the Maine Forest Products Council.
The state’s early intervention program began last June, a period when spruce budworms are emerging from hibernation and are the most destructive. The treatment is only applied in areas teeming with spruce budworms and where landowners have opted in. Biological insecticides that target only the caterpillars and are less toxic to other creatures have replaced the broad-spectrum pesticides used in the last outbreak, according to the forest service.
“These smaller pockets are getting sprayed before they expand, so there’s a lot less spraying than before,” Mech said.
Maine commercial and private landowners have been working with the state and federal governments to fund the early intervention program, with an initial commitment of $14 million. In May, the federal government added another $10 million. The state approved an additional $2 million last year to go toward future spraying. The Maine Forest Service is also looking for small woodlot owners to participate in a cost-share program that will begin next year.
The early intervention strategy is still in its beginning stages, but so far it looks like it has prevented development of a large population of spruce budworms, said Neil Thompson, the Applied Forest Management program lead at the University of Maine at Fort Kent.
But Maine will continue to be at risk as long as spruce budworm moths, which can fly 200 miles, continue to come from Quebec.
“Ten years is a very reasonable expectation of how long this will continue to be an issue, until the source population in Quebec is concluded,” Thompson said. “Then I think we’re out of the woods.”
Lori Valigra reports on the environment for the BDN’s Maine Focus investigative team. Email her at lvaligra@bangordailynews.com. Support for this reporting is provided by the Unity Foundation, a fund at the Maine Community Foundation and donations by BDN readers.