Recent requests for information has prompted us to share what we know about "jumping worms," another in a long list of invasive species that could have a negative impact on our landscapes and natural areas. In the words of Gilda Radner, "It's always something. If it isn't one thing – it's another."
Jumping worms (Amynthas spp.) are among the approximately 6,000 species of terrestrial earthworms in the world. Jumping worms are also known as crazy worms or snake worms, names that describe their wild movement. They violently writhe and squirm when disturbed and move more like a snake than an earthworm. Watch the activity in this YouTube video. Jumping worms are 3-5 inches long (some up to seven inches in length) and dark brown to gray in color rather than reddish-brown. They are darker and smoother than our usual earthworms such as nightcrawlers (Lumbricus terrestris) and garden worms. Jumping worms have a milky-white to gray clitellum (the band around the body of an earthworm) that is smooth, not raised above the body (Figure 1). The clitellum completely encircles the body unlike on European earthworms where the clitellum does not wrap entirely around the worm.
Jumping worms are native to southeast Asia and are believed to have arrived in North America with potted plants, nursery stock or soil. Jumping worms have been in the southeastern United States for many years, including in the Great Smoky Mountains. In the past few years, they were found in Illinois and Wisconsin. As far as we know, jumping worms have not been reported in Iowa, but with the ease of movement as fishing bait and within plants and soil, it's probably only a matter of time. Jumping worms are easy to spread because they spend the winter in the ground as small, pinhead-size, round, black or brown cocoons (earthworm cocoons contain eggs) that can move with soil, plants, mulch or stuck on shoes.
Jumping worms are surface-dwellers; they consume leaf litter and organic matter at the soil surface. Once established, populations can build quickly. They can outcompete and push out the other earthworms and degrade ecosystems, especially forests and woodlands by stripping the soil surface of protective organic matter. For a general overview of the harmful ecological effects of earthworms, see the Minnesota Department of Natural Resources website. You can download a "Contain Those Crawlers" poster.
Life Cycle: It appears that jumping worms do not survive as worms through the winter in the Midwest. When the worms reproduce in the fall they produce cocoons that drop to the soil and survive the winter. The cocoons hatch to start the cycle over and the population builds rapidly through two generations per season. Jumping worms are parthenogenic; each worm can reproduce on its own without mating. Jumping worms reach maturity within 60 days of hatching. Adult jumping worms do not become apparent until late June and early July and populations are largest in early fall.
Prevention: There is no cure or eradication for earthworms (European or Asian). Therefore, the goal is to prevent their spread and monitor for their presence. Here are tips from the Wisconsin DNR:
- Educate yourself and others to recognize jumping worms and watch for signs of their presence. If you find them, report them to Iowa State University Extension and Outreach Plant and Insect Diagnostic Clinic (firstname.lastname@example.org).
- Arrive clean, leave clean. Clean soil and debris from vehicles, equipment, tools and personal gear before moving to and from a work or recreational area.
- Check plants, landscape and materials for the presence of jumping worms; purchase those that appear to be free of jumping worms.
- Compost and mulch that is heated to appropriate temperatures and duration to reduce pathogens will also reduce jumping worms.
- Plant sales have been canceled due to concern for transport of the worm cocoons. At a minimum, gardeners who know they have jumping worms should exclude themselves from taking part in plant exchanges to prevent the spread.