Editor’s note: This article by Claire Potter was first published in the Valley News on May 22.
SHARON — A snake-like earthworm has forced the Baxter Memorial Library to ban perennials from its Plant, Book & Bake Sale on June 4. And in Canaan, New Hampshire, the library trustees decided to cancel their plant sale altogether because of the Asian jumping worm.
“It just seems that they’ve gotten a little out of hand,” said Shana Ronayne Hickman, the director of the Baxter Memorial Library.
Jumping worms were first reported in New Hampshire about five years ago, according to New Hampshire Forest Health. Since then, they’ve spread fast, although the most severe infestations are still farther south. New Hampshire raised awareness about the invasive, and by 2021, there were over 200 new reports of jumping worms dotting every county in the state.
In Vermont, reports of jumping worms in iNaturalist have accelerated since 2017, spreading to every county except Essex and Orleans in the north.
“They have a voracious appetite for organic matter,” said Vincent Noga, a home garden educator at University of New Hampshire Extension. Their appetite is so insatiable that it transforms the environments they invade.
Jumping worms transform soil. As they eat the rich, organic matter in the topsoil, they excrete a grainy material not unlike coffee grounds.
“The soil becomes this crumbly texture rather than loose, fluffy or dense soil,” Noga said. The roots of plants can no longer grip the soil; they struggle to draw in the nutrients and water they need. Noga has even heard reports of gardeners being able to lift a perennial out of the soil by the roots.
Jumping worms are a growing threat to forests too, warns the U.S. Forest Service. They eat away the leaf litter on the forest floor, destroying the thousands of tiny animals that live in the dead leaves. Soon, the forest becomes inhospitable to native plants and animals once they can no longer take refuge in the environment that they adapted to.
At first glance, jumping worms are difficult to differentiate from the relatively benign earthworms that Europeans brought to North America hundreds of years ago. The bands near their mouths are more white than pink, and they stay closer to the surface of the soil.
But their erratic, snake-like behavior sets them apart, Noga said. They writhe and slither, moving at speeds out of reach to a worm that is merely able to inch and wiggle. They thrash and jump when they are disturbed, which gave them their name.
So far, there is no clear way to control the jumping worm. They are not a major agricultural pest, and most research funding is directed toward agriculture rather than home gardens or forests, Noga said.
For an avid gardener, it’s emotional to find jumping worms, he said, in part because it’s hard not to feel responsible. “I sense frustration and panic from homeowners who call me,” he said.
Still, homeowners grappling with jumping worms have options. Extreme heat will kill the worms, along with many beneficial soil organisms. Heating soil to any real depth in New England with plastic is difficult, but 72 hours at 104 degrees Fahrenheit can kill the worms, Noga said.
University of Minnesota Extension recommends other ways to control their populations, from spreading coconut mulch to pouring solutions of Mrs. Meyer’s dish soap onto the soil.
Jumping worms first arrived in the United States from Japan decades ago, but worms, unlike other invasive insects, cannot fly and so they spread slowly, Noga said.
“They’re earthworms. People weren’t paying attention until it was wreaking havoc in certain areas and the population grew to the point to have negative impact on soils,” he said. They reproduce asexually, so just one worm can spawn an infestation. The adult worms die in winter, but their small, mustard-seed-like eggs survive.
They spread most quickly when people move infested soil and compost, or swap and buy plants, Noga said. But canceling perennial sales and swaps is not the only way to control the spread.
“If you wash the roots really thoroughly, you can come close to eliminating risk, if you’re really careful. (The egg cocoons) are so small that realistically they are easily missed or overlooked,” Noga said.
The Plainfield, New Hampshire, Community Plant Sale, one of the Plainfield Community Church’s biggest annual fundraisers, included perennials that were carefully screened for jumping worms, said Ruth Bassette, who coordinated the sale. The plants came from experienced gardeners well aware of the threat, she said. The roots were thoroughly washed, and then the plants were stored at Bassette’s home for about a month before the sale. She made sure there was no sign of jumping worms.
But requiring donors, especially when so many are elderly, to wash their plants was too much to ask in Strafford, said Ronayne Hickman.
Still, the Baxter Memorial Library’s sale remains an event to be celebrated, she said, and unlike last year, they will have live music.
