All over the eastern half of the state, trees have lost their leaves this spring and summer. The culprit is the caterpillar stage of the gypsy moth. And the hungry little caterpillars are happy the weather’s been so dry recently.
Forester Felicia Andre of the state Department of Conservation and Recreation pointed to some dark little packets attached to a leafless branch of an oak tree in Hopkinton.
“So this branch has died and the bark is peeling off of it, and it’s curled over, and inside as I’m peeling it off, I’m seeing just a ton of pupae here," she said. "Yeah, that’s pretty gross.”
Crawling on the branch next to it was a fuzzy little guy with red spots on his back. “And here we have a live caterpillar," she said. "So you have full grown caterpillar’s probably looking for a spot to start just going into pupae.”
As she talked, something very small and slimy fell out of the trees and landed on the reporter's hand. "It’s caterpillar poop,” Andre said, laughing.
That’s just one of the hazards in a forest full of gypsy moth caterpillars. Above, there wasn't much to provide any shade.
“It looks like it’s fall or spring," Andre said. "There’s just no leaves, and what little bit of leaves there are are so tiny, it’s kind of a little faint hint of green.”
One thing about gypsy moths, they’re not that discriminating in their tastes. “Anything green, they’ll eat it,” she said.
Andre has done a survey of the damage from a plane, and she’s seen patches of defoliation like this all over.
“Throughout the Cape, Plymouth, Quabbin is hammered, the areas around Worcester, Berlin, Clinton. Where it’s hitting, it’s hitting really hard.”
“And this is the first major outbreak we’ve had in 35 years,” said Joe Elkinton is a professor of entomology at University of Massachusetts.“The last really big one was in 1981. That was the biggest one in history when virtually the entire state of Massachusetts was defoliated.”
Things started getting better eight years later, when a fungus from Japan showed up, and its favorite food was gypsy moths.
“And the fungus spread all over New England, and then continued to spread in subsequent years," said Elkinton. "And since that time the fungus has prevented gypsy moth outbreaks from occurring.”
But the fungus needs really moist conditions to flourish. And last year’s spring there was a drought.
“And then this year’s been even drier," Elkinton said. "We’ve had extremely dry conditions in June especially. So the fungus that would normally cause a lot of mortality to gypsy moth caterpillars is not operating, and so the gypsy moth outbreak has proceeded.”
And there’s really nothing that can stop it at this point. Both Elkinton and Andre said the state’s not in the business of aerial spraying of pesticides anymore. And it’d be too late this year anyway. The caterpillars are almost done with their feast, and they’ll begin their shift into becoming moths over the next week or two.
So the damage is done. But, “I wouldn’t worry until we’ve had several years of this in a row,” said Andre. Just because the leaves are eaten, she pointed out, it doesn’t mean the trees are dead. “Like right now, in a lot of these areas it’s the first time, so these trees will recover, probably see full leaf out again by the end of July.”
And as long as we get some rain next spring, she says, the fungus will be back doing its thing, the gypsy moth caterpillars will have their mortal enemy back, and the leaves should be back on the trees.
