How a caterpillar native to Minnesota made its forests fuel for wildfires
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The wildfires that have scorched 45 square miles of forest in northern Minnesota were driven by unusually hot, dry weather and fierce winds. But a native insect called the spruce budworm also played a key role in creating a forest primed with flammable fuel to feed a raging wildfire.
The budworm is a caterpillar that devours the buds and needles on balsam fir and white spruce. But despite its name, it really loves balsam, which grows in thickets underneath taller pine trees. “It’s like candy to it,” said Duluth-based logger Josh Hull.
For the past decade, Minnesota’s Arrowhead region has been ground zero for a spruce budworm outbreak that infested trees over 2,000 square miles of forest in just the past four years, according to the Minnesota Department of Natural Resources.
Spruce budworm didn’t used to be a cause for much concern. They cycle through different parts of the forest every 30-60 years. Naturally occurring small fires cleared out much of the balsam understory and kept the pest in check. Balsam was also logged from the forest to make paper.
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But those markets for balsam have dwindled. And for the past many decades, land managers have suppressed most fires that have ignited on the landscape. As a result, balsam has been allowed to grow denser and older, creating an ideal environment for the spruce budworm to spread and thrive.
That creates an unhealthy forest that is extremely prone to wildfire.
“The balsam burns fine when it’s alive and green,” said Tristan Nelson, a forester with the North St. Louis Soil and Water Conservation District. “But when it’s dead, it’s way worse. I mean, it’s basically a matchstick standing there waiting to be lit.”
Eric Otto, forest health specialist for the Minnesota DNR, said a recent study found that the “peak of fire potential is five to eight years after trees die” from a spruce budworm outbreak, which lines up, he said, with when trees in the areas that burned so quickly were first attacked by budworm.
During a spruce budworm outbreak, the trees “look so gross,” said Beth Kleinke, a Duluth-based conservationist who works with forest landowners for the U.S. Department of Agriculture.
In June “the trees are just covered in worms,” she said. Then, later in the fall they emerge as moths. “And the trees would just be moving with moths.”
The dead balsam acts as a potent “ladder fuel,” helping fire climb into the forest canopy, where hot, howling winds then blow burning embers to neighboring trees. Minnesota’s red and white pines are built to withstand low-intensity ground fires. They have a thick, protective bark and they shed their lower limbs, explained Kleinke.
“It’s when there’s a super dense understory of balsam or spruce that provides a ladder for the fire to get up into the canopy that you see more damage,” she said.
Fire resiliency
The day after the Camp House Fire erupted near the small town of Brimson, forcing hundreds of people to evacuate, Gloria Erickson was tearful thinking about the homeowners in the area she has worked with to try to make their properties better protected from wildfire.
“It’s what we’ve been doing for years, and I’m hoping it’s paid off,” said Erickson, who works as the Firewise coordinator for St. Louis County. She works with landowners to create what’s called defensible space around their homes–essentially a buffer zone to help keep fire away.
She helps communities better prepare for wildfires, which are a natural part of the ecosystem in northern Minnesota’s boreal forests.
“People need to understand that we all have a role to play, and we all are part of the way that we can be more resilient to fire,” she said.
But it’s been an education process for many. When she first began over a decade ago, Erickson said people were appalled when she suggested removing all balsam fir trees within 30 feet of their homes.
“They looked at me as if I was asking them to kill their first born,” she recalled. And she gets it. She said when she first moved to the Ely area from the Twin Cities, she thought you weren’t supposed to touch the forest.
“But since we have this combination of not thinning those balsams, and suppression of fire for over 100 years, when the spruce budworm came in, it just devastated the forest up here,” she said.
Bringing back the forest
About 30 miles south of Brimson, Jason Tuttle strides through the forest on his property near Duluth and points out a small balsam fir that’s been killed by budworm.
“You can see how dry and brittle it is. It goes up with a lighter,” he said.
But there aren’t many balsam trees left on Tuttle’s 90 acres. With the help of a federal grant, he’s thinned out a forest that was once so thick with balsam he could barely walk through it.
“They’re inches apart. These trees grow so tight together. So I never really walked around in here. And after all this work got done, you look at your property and you’re like, ‘Wow! Do I have a piece of property here that looks amazing.’”
There are now big open clearings where he’s planted thousands of new trees — white and red pine, maples and oaks, wild plum trees.
“So the whole deal is to bring it back to its original state before it got clear cut 100 years ago,” he explained.
Tuttle works for the National Nuclear Security Administration at Los Alamos National Laboratory in New Mexico. But he grew up near Brimson, where he developed a passion for Minnesota’s northern forests.
He knows families that lost homes in the wildfires. And he didn’t want a fire to take hold on his property near Duluth and spread to nearby homes.
“It’s like, ‘boy, I own a big piece of property here. I sure would hate to see something happen and the whole area burns down,’ you know.”
He connected with Beth Klienke, who helped him secure a federal grant to remove the balsam from his land and replant it with a variety of other trees. The funding comes from the Environmental Quality Incentive Program, which was authorized by Congress in the 2018 Farm Bill, signed into law by President Donald Trump.
It’s the kind of work that’s needed across northeast Minnesota. But it’s expensive. It costs about $2,000 or more to treat one acre, Kleinke said. Last year alone spruce budworm killed trees over more than 700,000 acres, in the largest infestation in more than 60 years.
While there are some grants and cost-sharing programs available, there aren’t many commercial markets for balsam wood or pulp to help offset the cost.
Josh Hull, the logger who cleared Tuttle’s land, hauled some of the balsam to a power plant in Duluth that burns biomass. But the rest he mulched and left on the forest floor.
Hull has done hundreds of projects like this over the past decade. And after these fires, he said he’ll have more work than he can handle.
“I have a lot of customers up through the Brimson area that have already said, hey, when this calms down, I want you to come look at my property and see what we can do. How can we help get this forest regenerated again?”
He’s also had customers tell him that because of his work clearing dead or dying trees, their home was saved or their woods were spared.
“And it’s not just just one here, one there. There have been numerous customers throughout that area that have just called to say, ‘I’m glad that we did what we did, because it made a difference,’” he said.
Gloria Erickson is hearing the same thing. She said she’s heard from at least two homeowners she worked with whose properties survived the blaze.
Still, she said it’s hard not to feel overwhelmed.
“You can work and work and work with the community and landowners, and you can see so much work being done, and then you drive just a little ways away, and it’s a disaster.” Erickson said.
