Drive around southern Wisconsin, and you’ll eventually see stretches of dead trees from the highway. They are ghosts, haunted by emerald ash borer.
Warming winters have encouraged the spread of invasive pests like this tiny, green beetle, first discovered in the state in 2008. It got a helping hand from humans, hitching rides in firewood and young nursery plants across state and county lines. Exotic, tree-killing pests can, in turn, make climate change worse when they limit forests’ ability to lock up planet-warming carbon.
Wisconsin just had its warmest winter since the state started keeping records in 1895. This past winter, the average winter temperature was 28.3 degrees Fahrenheit, almost 10 degrees above normal. According to state climatologist Steve Vavrus, there’s no going back. In a state where winters have rapidly warmed since the late 90s, he called this winter an “exclamation point on a long-term trend.”
The state will likely continue to have winters that are warmer than what’s normal for the historical record. “I’m afraid that’s the direction we’re headed because we’re no longer in a stationary climate anymore,” Vavrus said.
This past winter has been declared Wisconsin’s warmest since record-keeping began in 1895. This 3-month statewide average temperature was 28.3°F, which is 9.8°F above normal (the 1991-2020 normal is 18.5°F). pic.twitter.com/JXr1aqrIcU
— Wisconsin State Climatology Office (@WI_ClimateSCO) March 8, 2024
That makes fending off pests harder.
“The ranges for a lot of invasives are getting larger,” said Melissa Johnson, pest survey specialist for the Wisconsin Tribal Conservation Advisory Council, or WTCAC. “We need to plan ahead for that.”
Tracking their spread is a key part of the effort. Johnson, an Oneida citizen, leads a federally funded pest survey across tribal land in the state. She said the cooperation between the U.S. Department of Agriculture’s plant health inspection service and WTCAC is unique nationwide and fills a critical gap for tribes in Wisconsin: Before it began around five years ago, tribal forests weren’t included in the state-run surveys.
For the 11 Wisconsin tribes they work with, Johnson said, “the more knowledge they have about their land, the better. And it’s not like an insect knows reservation boundaries or county boundaries.”
What they find helps inform tribal forest management and preserve wood from culturally important trees like black ash, which Haudenosaunee tribes have used to weave baskets for thousands of years.
Last July, I met Johnson and her interns at a wild, grassy field in the Oneida reservation west of Green Bay. She had five interns working across the state.
Deven Metoxen-Hamilton, a senior wildlife ecology major at University of Wisconsin-Stevens Point and Oneida tribal member, checked a trap hanging from an oak tree. It looked like a long stack of green plastic funnels, which drew bugs down to a cup. He unscrewed the cup and brought it to the trunk of his car, which he had turned into a makeshift laboratory.
The liquid inside the cup looked like lime Kool-Aid, spiked with bees, beetles, wasps and moths. “It’s antifreeze coolant. We mix it with water,” he explained. “Basically a solution we use at the bottom of the trap, to kill or immobilize the bugs.”
The mixture also helps preserve the samples.
Tribes decide what pests they want to look for, and the survey team sets up traps specific to each one, often loaded with pheromones to entice them. Many tribes, Johnson said, are concerned with identifying emerald ash borer, but it had already been found on Oneida land through the survey. Depending on the species, some traps get checked weekly, some every other week. Some are checked just once in the middle of the summer.
Metoxen-Hamilton’s first sample came from a trap for oak ambrosia beetles, which spread the oak wilt fungus, often deadly to red oaks. The disease is widespread in the southern half of the state, but it has yet to pervade northern Wisconsin. Overall, he was in charge of 20 traps last summer, monitoring also for Siberian silk moth, spongy moth and pine tree lappet — all of which can cause serious economic damage to Oneida’s forests.
Next, the trapped bugs were filtered from the solution and placed into a bag with an alcohol-soaked paper towel. The intern scribbled a label on it and stuck the bag in a lunchbox.
Later they’d send all the samples to a lab for identification.
“If they see something that’s of concern, they’ll send us a report back,” Johnson said.
Refilling the cup with fresh antifreeze, Metoxen-Hamilton said he almost wanted his summer job to be boring. He’d rather not find anything.
“It feels good to be doing this,” he said. “But then again, if you find something, it’s a good thing and a bad thing. Bad that it’s here. Good that you’ve detected it early.”
Then, it’s on to the next trap.
Deven’s brother, Ryan Metoxen-Hamilton, a junior at UW-Stevens Point majoring in biology, also worked on the survey last summer. The brothers grew up playing in the woods behind their house. They said it feels good to help steward the trees on their tribe’s land.
“I have always been interested in stuff like this for a long time,” said Ryan. “It started off with dinosaurs when I was a little kid.”
Ryan spent the summer in the Oneida apple orchard, monitoring traps for ambrosia beetle, false codling moth and European cherry fruit fly. He peered into a long trap made from stiff white plastic. I commented that it looked like a futuristic bug hotel.
“You can check in, but you can never leave,” Johnson joked.
All morning, the team drove to different sites: forests, parks, scruffy lots. There was a lot of ground to cover. None of them identify as “bug people.” They said they were motivated, rather, by the threat that non-native insects pose to the trees, birds and wildlife that they love.
“It is really overwhelming to try to meet this challenge,” Johnson said. “There are a lot of people out there working on it.”
Researchers are asking questions like what trees should we plant next? After ash gets wiped out in an area, how long do you wait before planting more? And, should we introduce emerald ash borer-killing wasps to the ecosystem?
“I think we’re making a little bit of progress, but I don’t know,” Johnson continued. “We’re gonna lose a lot of ash. That’s all I do know, for sure.”
One thing Johnson feels good about is working with the interns. The summer gig gets young people interested in natural resources and into the pipeline for future jobs in tribal conservation. Johnson herself started as a WTCAC intern, more than a decade ago. She worked as a forester for Oneida before she began coordinating the tribal pest survey.
The two brothers loaded their gear, turned up the country music and drove off to their next spot. They had a few more traps to check before the day’s work was over.
