ROCKINGHAM-Rural gardeners and farmers have long known that the common earthworm (also known as the nightcrawler or fishing worm) is one of the best things for improving soil health.
But in the case of the invasive jumping worm (also known as the snake worm or crazy worm), scientists are finding out that something that looks almost exactly like the well-known fishing worms we grew up with turns out to be very destructive to soils and eco-systems.
In Vermont, Amynthas tokioensis and Amynthas agrestis are the two most widespread species of jumping worms, making up about 95% of the invasive worms in the state.
"Jumping worms are a terrible nuisance," said Mae Masson, agricultural resource specialist for the Windham County Natural Resources Conservation District. "They're present nearly all over Vermont."
Earthworms aerate the soil with the channels they create, which also helps the soil absorb water when it rains. While making the channels, they eat plant debris and soil, and after it passes through them, their castings are full of nitrogen, which greatly enriches the soil and nourishes the plants.
Wise gardeners and farmers encourage a healthy earthworm population as essential for healthy soil and healthy, nutritious plants grown on it.
But now, along comes the jumping worm. To the untrained eye, it looks an awful lot like a nightcrawler. But its rapid thrashing and, at times, even jumping movements - like a jittery nightcrawler cranked up on caffeine - quickly gives it away.
Unlike nightcrawlers, jumping worms quickly transform soil into dry, granular pellets that are often compared to the appearance of discarded coffee grounds. Their castings alter the soil structure, depleting it of nutrients and soil organisms.
They can break down heavy wood mulch very rapidly, but without enriching or improving it.
And as a double threat, jumping worms can make the soil inhospitable to native species and garden plants, while invasive plants often thrive where jumping worms live.
At least 16 or as many as 19 species of earthworms live in Vermont's soil, depending on the source, and none of them are native. Until 12,000 years ago, the land that would become the Green Mountain state, like much of the continent, was trapped under a thick ice field during the last ice age. Massive glaciers scoured the earth down to bedrock, removing any earthworm populations.
Fourteen of the earthworm species now found here were introduced from Europe as early as the 1600s, and they have been largely helpful in improving Vermont's soils. Much more recently, a few other species have been introduced from Asia, the ones commonly called jumping worms.
Jumping worms have been identified in 12 of Vermont's 14 counties, with only the Northeast Kingdom free of them.
First found in North America well over a century ago, these worms spread through potted plants, compost, mulch, and farm equipment. They made themselves at home along waterways throughout New England, into the Midwest and to parts of the West Coast.
Due to their negative impact on soils, forests and ecosystems and the lack of natural enemies in their new environment, they are considered an invasive species.
Ways to fight back
According to vtinvasives.org, a website from the University of Vermont Extension, a few things can be done to help control jumping worms, and right now is the best time of year to identify them, as they are very active from June to September, they exist in large numbers, and the adults of the species are large enough to see and identify easily starting in August.
The adult jumping worms have a fully formed telltale clitellum - a raised band of tissue that forms a ring around the worm's body - about a quarter of the invertebrate's length from the head.
"In jumping worms, it goes all around the body and is clearly offset from the body by color. The clitellum of European earthworms only stretches part way around the body, much like a saddle on a horse," according to the Vermont Invasives site.
Of course, the jumping worms' rapid, erratic, sidewinding movements are also a collective major identifying trait. The number of nicknames for the species - crazy snake worms, crazy worms, snake worms, Alabama jumpers, Georgia jumpers, and Jersey wrigglers, to name a few - measures the extent to which they are identified by their movements.
Stopping the spread
"Checking your compost and mulch sources is key to not bringing them into your property," said Masson, who also recommended two other steps for gardeners and farmers.
"In the spring, till the top 2 to 3 inches of soil where you're planting to disturb worm cocoons. Worms die off in the winter, but cocoon overwinter," she said.
"And finally, solarize," Masson said. "Cover your growing area with black or opaque plastic to allow the sun to heat up the area enough to kill off the worms. You can also solarize any organic material in plastic bags before adding to your garden."
According to the UVM Extension, one way to identify the presence of jumping worms in your garden, woods, or lawn is to "create a diluted dish soap mixture [...] with a few spritzes of the soap into two gallons of water. Pouring the solution slowly over the soil will drive worms to the surface without harming plants."
Everyone who gardens can help stop the spread of this invasive by carefully paying attention to several things:
• Remove soil and debris from vehicles, equipment, footwear, and personal gear before going to and from work and recreational areas.
• Avoid practices that spread earthworms into untreated soil or compost, including carefully inspecting the root balls of plants and trees bought at nurseries. It's not always possible, but plant using bare root stock or seeds when you can.
• Do not buy jumping worms for composting, vermicomposting, gardening, or bait.
• A vital step is to make sure to sell, purchase, or trade only compost and mulch that was heated to appropriate temperatures and duration following protocols that reduce pathogens.
Best management practices by landscapers and nurseries for removing jumping worms include solar heating the soil under plastic or tarps for several weeks, hand picking the worms and destroying them, and top-dressing treated areas with noninfested mulch or compost.
Jumping worms are often found clumped together. If you find them, do not remove them to other areas or to the forest. They can be hand-picked and destroyed by soaking them in rubbing alcohol, by putting them in a bucket of soapy water for 15 minutes to two hours, or by sealing them in plastic bags, putting the bag in a freezer for a few hours, and then disposing of them in the trash.
One of the leading experts on jumping worms is Josef Görres, Ph.D., an associate professor of ecological soil management at the University of Vermont's Agriculture and Life Sciences Department.
More information about research from Görres and his team is available at uvm.edu/extension/news/invasion-jumping-worms.
This News item by Robert F. Smith was written for The Commons.