Mass. Crawling With Caterpillars
Some are tiny, dark and hairy. Others are tiny, green and white. All are voracious. And they've been chomping away by the millions from Cape Cod to the Berkshires.
Entomologists say this spring brought a population explosion of caterpillars in Massachusetts.
Some, like the tent caterpillar and gypsy moth caterpillar, have been dining on Massachusetts greenery for decades in cyclical outbreaks. But the winter moth caterpillar from Europe, which has been munching on coastal Massachusetts, is a new menace to the state's maples, apples and blueberries.
"It's a scientific puzzle," said Bob Childs, director of the Urban Forestry Diagnostic Laboratory at the University of Massachusetts' Amherst campus, where entomologists are trying to figure out what may have led to a boom this spring in both native and introduced species.
"There has to have been something missing from nature's system of checks and balances that has allowed them to be so successful," Childs said. "We've never seen numbers of the native species like this."
"We thought last year was bad, but this year is really the year of the caterpillar," said Deborah Swanson, a horticulturist for the university extension in Plymouth County, which has been hard hit by the infestations.
"We have forest tent caterpillars, eastern tent caterpillars, cankerworms, loopers, gypsy moths, and, of course, the winter moth," she said. "We've had hundreds of calls from people wondering what happened to their trees."
Some stands of oaks in Freetown, defoliated in early spring by the winter moth caterpillar, have started to send out new leaves just in time to face a second defoliation by gypsy moth caterpillars, said Childs.
"It's awful," said Freetown Tree Warden Gary Loranger. "It looks like winter when you drive through town."
Healthy trees can withstand occasional defoliation, but Swanson said worried homeowners should ensure that their favorite shade trees get adequate water in the hot summer months.
No one knows how the winter moth, named for its strange early winter mating ritual, got to coastal Massachusetts. The only other areas in the United States where outbreaks have been reported are Washington and Oregon. But the winter moth has been in Nova Scotia for decades, Childs said.
Now, it is found from Manchester-by-the-Sea to the South Shore, Cape Cod and Martha's Vineyard. This spring it was reported for the first time in Rhode Island, Childs said.
Some blueberry growers have had most of their crop wiped out, said Dominic Marini of East Bridgewater, a past president of the Massachusetts Cultivated Blueberry Growers Association. UMass researchers are now looking for natural predators, parasites and diseases that could keep it in check.
The first sign of trouble is an unseasonable blizzard of moths swarming to mate in late November and early December, Swanson said. They emerge is such numbers that tree trunks appear "covered in moving fur" as the winged males flap their wings to attract the flightless females, she said.
The tiny larvae emerge in early spring, just as the trees are beginning to bud, and squeeze between the protective scales to get into the bud and eat the forming leaves and blossoms. And without blossoms there are no fruit.
Their favorite targets seem to be maples and apples, including flowering crabapples, she said, but they can also damage other plants, including roses.
By Trudy Tynan