Pine forests in New England could soon be at the mercy of an incredibly destructive insect. The southern pine beetle is making its way north. And a new study says climate change could speed up its migration.
Shotgun pellet holes and popcorn. Those are two things you wouldn’t think to mix. But when it comes to the southern pine beetle, both are tell-tale signs of an infestation.
“Here’s a dead tree. Or almost dead anyway. What was that line from the “Princess Bride”?” asked Thomas Worthley, who teaches forestry at UConn.
As it turns out, the tree is only mostly dead. As we stand in a Connecticut forest, he points out two tell-tale signs of pine beetle infestation. Shotgun pellet holes and popcorn.
“I don’t know if you can see the shotgun effect of holes here on the bark. That’s the kind of thing that southern pine beetle would do,” Worthley said. “A bunch would bore in little holes. You’d get these kind of popcorn-shaped exudation of pitch. The bad pun is that the tree is trying to pitch out the beetle.”
In big groups, these insects can swarm trees and cause massive damage.
The U.S. Department of Agriculture said the southern pine beetle is the most destructive insect pest in the southeastern states. And now, a new study out of Columbia University indicates climate change could expedite its journey north.
“We’ll be dealing with mortality in our trees from something we’ve never experienced before,” said Corey Lesk, one of the study's authors.
In the paper, he modeled how carbon emissions drive up winter temperatures. And he paired that data with beetle biology -- looking at how cold a winter needs to be before it kills a beetle.
What he found out is that warmer winters mean more beetle survivors.
Writing in the journal Nature Climate Change, he said that means New England’s door could be wide open to the southern pine beetle.
“I think it’s fairly plausible to imagine pretty widespread mortality in the 2020s,” Lesk said.
Claire Rutledge, an entomologist who works for the state of Connecticut, said southern pine beetles are already here. Right now, she said numbers are small and only a handful popped up in traps this year.
But the beetles were found in the New Jersey pine barrens only a few years ago. And Rutledge said they’re now also on Long Island.
“They’re very tiny little beetles. It’s relatively easy for them to become aerial plankton,” Rutledge said. “To be lifted up by the wind and swept over and dropped.”
In 2015, she said it looked like some beetles did just that -- soaring over Long Island Sound and plopping down in several Connecticut towns.
This year, she said only a handful popped up, which means the jury is still out on whether the southern pine beetle is established enough to do mass attacks on healthy trees.
But Rutledge agrees. The beetles are coming. And they could wipe out an iconic Connecticut tree.
“I think for Connecticut our major concern really is the pitch pine,” Rutledge said.
The study warned that even more types of trees could be threatened by the mid-to-late 21st century -- as the pine beetle moves over New England and southeastern Canada.
“More north and west they’ll find more native red pine as part of the mix in the forest,” Worthley said. “New Hampshire has a larger red pine component than we do. But then up there you also find a species called jack pine. That’s a northern species that grows in pretty dense, almost pure stands that could be seriously affected.”
The USDA says the last major multi-state beetle outbreak in the early 2000s resulted in more than $1 billion in economic losses to a region in the southern Appalachian Mountains.