Zebra mussels. Emerald Ash borers. Buckthorn. Eurasian milfoil. These are some of the most well-known and destructive non-native species that have invaded Minnesota’s lakes and forests, threatening ecosystems both in water and on land.
Now add the jumping worm to that ignominious list of invasive species in Minnesota.
These destructive earthworms, native to Asia, can quickly degrade soils and damage garden plants and lawns.
They’re called “jumping worms” because of their unusual, aggressive behavior. When disturbed, they move like a snake, writhing and squiggling, and sometimes appear to be jumping.
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They live and feed in the leaf litter in the top 2 inches of soil, and can kill plants, strip the soil of nutrients and trigger severe erosion. The worms change the soil texture to appear like coffee grounds or cat litter.
Lee Frelich, director of the center for forest ecology at the University of Minnesota, said he never imagined such a horrific invasive species.
“There are invasive species like the emerald ash borer that might wipe out one or maybe a handful of species of trees,” he said. Similarly, species like buckthorn, he notes, are destructive, but don’t kill all the native plants where they take root.
“Here you have an invader that can literally destroy the soil. So it's a whole different category of invasive species that can alter the ecosystem at its most fundamental,” he said.
Frelich first spotted the species at Loring Park in downtown Minneapolis in 2006, when he noticed some odd-looking hostas. When he reached down to touch the plants, he realized they weren't attached to the ground. Jumping worms had eaten around the roots and detached the plants from the soil.
The worms weren’t seen again for a while. Frelich thinks it likely took them several years to undergo some form of selection and adaptation to Minnesota’s climate.
“And then they suddenly exploded across the landscape,” he said. “And we're just at the beginning of that explosion right now in Minnesota.”
Frelich said the worms have spread to Rochester, to steep forested hillsides in southeastern Minnesota, and throughout the Twin Cities, including to the Minnesota Landscape Arboretum in Chaska.
“There are some forests on fairly steep slopes at the Arboretum where you step on the soil and you virtually slide down the hill because the soil is so loose,” Frelich said.
Earthworms are not native to Minnesota and other northern states. People spread them by moving potted plants, soil, compost, mulch, sod and fishing bait.
The Minnesota Department of Natural Resources is cautioning gardeners and anglers to be on the lookout for the invasive jumping worms.
“The good news is, jumping worms are not well established in Minnesota and there are actions people can take to prevent their spread,” said Laura Van Riper, DNR terrestrial invasive species coordinator.
“We need gardeners and anglers to be vigilant and to contact the DNR when they think they’ve found jumping worms,” Van Riper said.
The DNR warns people not to buy worms advertised as jumping worms, “snake worms,” “Alabama jumpers” or “crazy worms” for any purpose. Unwanted bait should be thrown in the trash. Gardeners should inspect mulch or plants they purchase for worms.
Meanwhile Frelich is leading a team of University of Minnesota researchers studying how jumping worms are spreading throughout Minnesota, whether low temperatures could limit their spread, and how they might be controlled.
They’ll also compare erosion rates and native plant populations in areas already infested with worms to see if there are fewer plants in those areas, compared with spots that haven’t yet been invaded.
The goal is to work with the Minnesota DNR to develop best practices to prevent the spread of jumping worms across the state. But Frelich is concerned it may be too late to stop them.
“Given the number of reports we’re getting of these worms, I'm starting to lean towards maybe it's too late,” Frelich said. “But we don't know for sure right now, and that's one of the things we're going to find out.”
If you think you’ve found jumping worms, the Minnesota DNR asks you to take high resolution photos, showing the ring around the worm’s body in relation to its head, and report them using www.eddmaps.org, or contact the DNR at 888-646-6367 or firstname.lastname@example.org.