These hungry, ‘muscular’ snake worms are ‘widespread’ in New Hampshire

The worms are most commonly found in leaf-litter and mulch.

The worms are most commonly found in leaf-litter and mulch. J. GREEN—Nebraska Extension, courtesy

By CLAIRE SULLIVAN

New Hampshire Bulletin

Published: 07-17-2024 8:56 AM

If you’re wondering what happened to your once-beautiful soil, diminished to the texture of coffee grounds, you’re not crazy. But maybe your worms are.

So-called crazy worms – also commonly known as jumping or snake worms because of their quick, thrashing movements – are an invasive species from Asia first found in New Hampshire about seven years ago. They are a hungry bunch, devouring organic matter at a much faster rate than European earthworms.

“They are definitely considered to be widespread at this point throughout New England,” said Steph Sosinski, manager of the University of New Hampshire Extension’s Home Horticulture Program. “And not quite up to the very northern parts of Maine yet, but certainly in our area and south, they’re widespread at this point.”

The adult worms are characterized best by the way they wriggle. “They’re very muscular worms, so they move around a lot,” Sosinski said. “They move in a serpentine motion, kind of like a snake does, and if you touch them or pick them up, they’re highly active.”

They can also be distinguished from other worms by their grayish-brown color and their bands, ranging in color from creamy white to tan, that wrap all the way around the body and are closer to the tips of their heads than other earthworms, Sosinski said.

The younger worms are harder to discern than the adults. And the cocoons, which are small, dark, and circular, can be extremely difficult to spot. That’s what makes it so easy to unknowingly buy soil, mulch, or plants with soon-to-be worms, or accidentally track them into your garden on your shoes. 

“Their eggs are virtually impossible to identify by your eye alone,” Sosinski said, “so, they blend into the soil.”

The worms are considered an annual species in New Hampshire, they said, meaning they die off each year with the freezing temperatures. But they have no trouble starting over, with one study finding a worm can produce one cocoon every one to two days in the summer and fall, Sosinski said. 

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“That’s really one of the drivers for how quickly they spread and how quickly they can become a major problem,” they said.

The cocoons hang out through the cold and hatch in the warmer months. “They’ve been shown to be viable for two years, maybe more,” Sosinski said. “So, if they don’t hatch … that first year, they’ll still be there for the next year.”

Once they hatch, they take about 60 to 90 days to mature to adults, Sosinski said.

The worms are most commonly found in leaf-litter and mulch, and are often introduced into gardens unwittingly through plant sales, Sosinski said. They typically reside in the top 4 inches of the soil.

There’s been a recent decline in jumping worm reports. In 2021, there were 416; last year, there were about 200, Sosinski said. That doesn’t necessarily mean the worms are becoming less prevalent, though.

“It could be that people are just starting to really get used to them or get educated on them,” Sosinski said. “Maybe they don’t feel like they need to report them at this point, because so many people have them in their own gardens.” 

The Department of Environmental Services, in a recent newsletter, told gardeners to watch out for the worms. “Even just one of these can disrupt an entire environment,” DES wrote.

When the worms eat organic matter, which provides nutrients for plants, they leave behind castings that have a grainy texture and are somewhat resistant to water, Sosinski said. The more of that good soil the worms turn poor, the harder it is for seeds to germinate or for shallow-rooted plants to take hold, they said.

“If they don’t have soil to hold on to, and they don’t have a way to hold their water,” Sosinski said, “… obviously, those plants aren’t gonna make it.”

Leaf litter, a popular chomping ground, serves as an important habitat and food source for other creatures, including insects, some small mammals, and birds, they said. That has a larger impact on the ecosystem.

“If that leaf litter starts to decompose at a faster rate than is natural in that ecosystem,” Sosinski said, “and then we start to see declines in some of these plants, biodiversity in general … can decline.”

On a large scale, it’s a difficult problem to manage. Since earthworms are usually seen as beneficial to gardens, “we’ve never really ever been in a situation where we needed to consider a vermicide,” Sosinski said, “so there’s nothing legal out there right now.”

Beyond that, the worms have made a home of the Granite State.

“At this point, these worms are so widespread, it would just be almost impossible to effectively regulate them,” Sosinski said. 

However, there’s a few things individuals can do.

Sosinski recommends that people “solar,” or heat treat, material they’re bringing onto their land. This could look like laying bags out in your driveway in the full sun for a day or two. For bulk products, people can wrap the material in clear plastic, which collects more heat than black plastic, to kill the worms and prevent them from escaping during the process, Sosinski said.

If you’re picking out worms from your garden, you can put them in soapy water to kill them. Sosinski also knows gardeners who put the worms in a large bucket with sand and a lid to dry them out. 

To prevent introducing the cocoons into your garden, you can rinse your tools and use a boot brush to scrape off your shoes, Sosinski said. They recommend buying plants with bare roots, if possible, so cocoons don’t sneak in. You can also soak and wash your plant roots to make sure they’re clean.

While the worms have done their damage to gardens across the state, they are still relatively recent residents.

“We are just still in the first few years of learning more about these worms,” Sosinski said. “There’s a lot of questions that still need to be answered.”