ASIAN JUMPING WORMS, shown here as juveniles at a recent talk in Middlebury, can pose a significant threat to gardens, lawns and forests. The creatures consume a key layer of organic matter in soil, which has a ripple effect on the surrounding environment.
Independent photo/Marin Howell

MIDDLEBURY — As warmer weather beckons Addison County residents outdoors this spring, there’s an uninvited guest they should keep watch for in their gardens, lawns and fields: jumping worms. 

The creepy-crawlies look similar to earthworms but are actually an invasive species originally from Asia that consumes and degrades soils, killing plants and setting off a cascading effect on the surrounding environment. 

“The reason why many people are worried about jumping worms, at least ecologists, is because they change woodlands a lot,” explained Josef Görres, professor of Ecological Soil Management at the University of Vermont. 

Nearly 100 community members packed the Congregational Church of Middlebury on April 23 to hear from Görres and other experts about how to identify and combat jumping worms. 

UVM postdoctoral researcher Maryam Nouri-Aiin and Emily Johnston, public outreach coordinator at the Addison County Solid Waste Management District, also spoke at the event. The presentation was sponsored by the Pollinator Pathway of Addison County, UVM Extension Master Gardener Program and Vermont Coverts: Woodlands for Wildlife.

GET TO KNOW THE WORM

Asian jumping worms likely first wriggled their way into the United States at the beginning of the 20th century, Görres said. 

How did they get here? 

“(The worms) probably came with trade with Japan,” Görres said. “First of all, here on the east coast, (likely) cherry blossoms brought them over for the first time, and there have probably been many more introductions since then.” 

The arrival of jumping worms was not the first time non-native worms had wreaked havoc on U.S. soils. The earthworms many gardeners welcome today came to North America with European settlers during the 1600s, infiltrating soil that was largely worm-free. 

 “They cause similar problems (to jumping worms) in that they change the soil properties and that changes many other things as well,” Görres said.

Jumping worms have compounded the impact of their European counterparts by causing their own trouble in invaded soils. 

They do so by devouring the upper organic layer of soil, altering its texture and composition. 

“That organic layer goes with a whole bunch of other things, such as seed bank of the forests, mycorrhizal (essentially symbiotic) connections to the roots, the roots themselves could be in there,” Görres said. “That’s where a lot of the fertility of the soil is, so once that goes away, things change.” 

Jumping worms consume the top layer of healthy, spongy soil and replace it with a granular soil with worm castings. This modified soil resembles large coffee grounds and lacks the nutrients certain plants, animals and other organisms need to survive. 

That structure also makes invaded soils more vulnerable to erosion, which can lead to further loss of nutrients. 

“Forest soils are not supposed to erode, even in big storms,” Görres said. “That organic layer is really holding things together very well, but once you have this modification by the Asiatic worms you have continuous erosion.” 

The alteration of soils has a ripple effect on the surrounding environment as it changes the soil composition and chemistry that many plants and animals rely on. As a result, a jumping worm invasion can result in loss of biodiversity. 

The worms can have a negative impact in and around agricultural fields, as they create burrows that allow nutrients to flow into nearby waterways more easily and for carbon dioxide to release into the atmosphere. 

Jumping worms also pose a threat to a key plant in Vermont: sugar maple trees. The worms significantly hinder the regeneration of maple trees by consuming the layer of leaf litter on forest floors, which leaves the trees more susceptible to insects and diseases. 

“So, buy a lot of maple syrup and put it in your cellar in case one day we run out,” Görres joked. 

SLOWING THE SPREAD 

The effect of jumping worms on their surrounding environment is significant, but Görres said there’s hope for slowing their spread and managing invasions. 

The first step is knowing how to identify jumping worms, which can resemble other earthworms like nightcrawlers. Unlike those worms, adult jumping worms have a smooth, milky-white collar known as a clitellum close to their head that wraps around their entire body. 

Adult jumping worms can also be distinguished by their thrashing movements. When disturbed, the worms flail or jump wildly from side to side, a characteristic that gives them their name. 

Knowing how to spot a jumping worm is a key part of preventing the spread of the invasive species, along with remaining vigilant about the use of soil, mulch and potted plants.  

“The best time to intervene in any kind of invasion is before the invasion happens,” Görres said. “Prevention is the cheapest way of dealing with the problem.” 

Görres said one way humans unknowingly spread jumping worms is through leaf mulch. 

“So, you rake your leaves, put them in a bag and take them somewhere else, and then someone else comes up and says, ‘Can I have some of that leaf mulch,’ and they take the leaf mulch and the worms with them,” he explained. 

Limiting the use of your leaf mulch to your own property is one way to prevent the spread of jumping worms. Other tips for preventing invasion include: 

• Checking the soil and roots of potted plants and trees for signs of jumping worms before planting them in your yard. 

• Cleaning equipment and tools of compost, soil and other debris before moving from one site to another. 

• Rinsing soil from the roots of seedlings and small plants before sharing or moving them. 

Johnston also cautioned residents to check the worms they purchase online or elsewhere to ensure they’re getting red wiggler or other earthworms and not their jumpy counterpart. 

“If it seems like a sketchy site or you get the worms and they look nothing like red wiggler worms, it’s a safe bet that they might not be red wigglers,” she said. “Err on the side of caution. It’s a lot about knowing your source because we do not want to spread this material.”  

Gardeners can also “solarize” their mulch or soil to try to eliminate jumping worms before use. Soil solarization consists of placing a clear plastic tarp over to heat up the soil underneath. 

Jumping worms can’t survive in temperatures of more than 150 degrees Fahrenheit, so solarizing can help kill both cocoons and adult worms. 

“Sterile is never 100% sterile, so there’s always something that survives, but at least you get the numbers down,” Görres said. 

As for those who find jumping worms on their property, there are some steps available to manage the invasion, such as hand plucking the worms from infiltrated soil. 

“If you have a routine of weeding, weed the worms as well. Put the worms into a bucket of soapy water and that will kill the worms and then you can put them on your compost pile safely,” Görres said. 

Görres noted there’s currently no registered vermicide available to combat jumping worms, though Nouri-Aiin is currently experimenting with the use of the mycoinsecticide BotaniGard to control the species. 

Nouri-Aiin emphasized those experiments have thus far only taken place inside a greenhouse environment and that its use or that of pesticides presents things to consider. 

“There’s always tradeoffs,” she said. “Sometimes it may be better to adapt to the worms. Maybe to use solarization, collect the leaves that might have juveniles and heat those. There are ways; it doesn’t have to be just pouring chemicals.” 

As community members wrestle with jumping worms and await further solutions, Görres encouraged residents to not let the creatures get the best of them. 

 “Let’s not leave this room without hope,” he said. “It’s really important to me that we get rid of some of that anxiety that goes with jumping worms.”