The Two Degree Difference: Gypsy Moths

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The population of gypsy moth caterpillars is growing in Vermont and the state’s trees are being damaged in the process.

“In certain areas now we’re seeing a lot of defoliation,” said Judy Rosovsky, state entomologist. “They’re eating the leaves and you’re hearing rain of their droppings.”

Rosovsky says gypsy moths were introduced by a French man named Trouvelot in 1869. He wanted to use the species to start a silk industry in the U.S, which was unsuccessful.
Now, the Vermont Agency of Agriculture is trying to knock down the population locally.

“The thing with invasive species is they don’t have natural enemies here that are going to eat them,” Rosovsky said.

Gypsy moth caterpillars typically go after oak trees first, before destroying the leaves of other trees and shrubs. A single gypsy moth can lay between 600-1,000 eggs at once.

“It is a stress on the tree and when trees accumulate stress it can have long-term health effects,” Rosovsky said. “They become weakened, they become more vulnerable to other insects and diseases that can attack them.”

Rosovsky says because it’s been so dry, a fungus that typically kills off the caterpillars hasn’t been abundant enough to keep the population under control. She says the state will consider a spray project in some areas in the fall, if necessary. Over the next few weeks, the gypsy moth caterpillars are expected to spin their cocoons before hatching into moths.

“If you see those egg masses, they’re sort of oval and beige on your tree trunk, you can scrape them off and dump them in soapy water to get rid of them,” Rosovsky said.

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