Gypsy moth caterpillars, a scourge of the forest canopy that hit the Northeast in the 1980s and then largely disappeared, have returned to parts of Eastern Massachusetts but don’t seem to be much of a concern in New Hampshire this year.
“We’ve received very few calls from homeowners reporting any sightings of gypsy moth. There are a few localized pockets, mainly in Southern New Hampshire, but nothing widespread,” said Jeremy DeLisle, infoline coordinator for UNH Cooperative Extension’s education center in Goffstown. “People send in pictures for identification. Most of what we have seen are eastern tent caterpillars.”
“I’ve talked to foresters . . . and they’re not extremely concerned about any gypsy moth outbreak this year,” he added.
The situation is different in parts of Massachusetts, where outbreaks have hit more than 100,000 acres from the Quabbin Reservoir to Cape Cod, making it the worst outbreak since 1981, according to news reports.
News stories from the Bay State will bring back memories to those who were out in New Hampshire woods three decades ago, as they’re full of tales of caterpillar numbers so great that their chewing is audible, as is the pitter-patter sound of a rain of caterpillar feces falling from on high.
Such outbreaks had cropped up every decade or so since the post-Civil War era, when the gypsy moth was accidentally brought here from Europe, and were growing worse until they were contained in the late 1980s by the deliberate release of a fungus called Entomophaga maimaiga, which consumes the caterpillars from the inside.
The fungus is native to the eastern U.S., so there were no concerns about introducing a new species, and its spores survive in the soil even when there aren’t many caterpillars around, so it can respond quickly to a new outbreak.
Officials in the Bay State think the fungus hasn’t worked well this year because of the dry weather, which isn’t kind to fungi.
That can’t be the whole answer, however, because it’s just as dry in much of New Hampshire.
It appears the outbreak is due at least part to the way that cyclical swings in gypsy moth populations occur in different areas. Massachusetts’s upsurge happened during a really dry time.
It’s not just the fungus that has tamed the gypsy moth, by the way. There’s a virus that can infect them and cause the caterpillars to climb to the tops of trees, where they literally melt and drip the virus onto the foliage below, to be eaten by other caterpillars. It is sometimes sprayed into woodlands to control outbreaks.
The question arises whether the gypsy moth outbreak might move north into New Hampshire later this summer. Probably not, said DeLisle.
“The good thing is that a lot of those caterpillars are already starting to pupate. Once they do that, they’ll go down into the soil and basically be done for the season,” he said.
Either way, he said, the best thing for homeowners to do is to “minimize drought stress” so that trees and shrubs aren’t vulnerable to any caterpillars.
“Trees are pretty stressed – we’re going into two years of dry times,” he said. “Deep watering is important.”
(David Brooks can be reached at 369-3313 or dbrooks@cmonitor.com or on Twitter @GraniteGeek.)
