Moths vs. flies
After every Thanksgiving, a mob of winter moths rise up from the dirt and swarm blizzard-style across New England.
“When I’m out at night driving, sometimes you’ll hit pockets of them, and it looks like it’s snowing,” said Janet Bowser, executive director of Wellesley’s Natural Resources Commission, which spends $20,000 spraying trees on town property each spring to keep them from being devoured by the moths.
In 2011, winter moths defoliated 89,000 acres of trees across the state, according to the Department of Conservation and Recreation. An early thaw followed by a cold snap killed many this spring, and their toll went down to about 10,000 acres.
Still, a crude estimate puts their numbers in the trillions, and growing; in the springtime, up to 100,000 caterpillars hatch on a tree and eat the leaves before they bud, leaving lacy skeletons.
This year, a team of researchers are importing special flies (pictured) that dine on winter moths from Canada. About 30,000 flies will be released in about 10 spots throughout Massachusetts, Rhode Island, and coastal Maine.