Jumping worm (Amynthas agrestis)

Synonyms: Pheretima agrestis, Metaphire agrestis

Common Names: Asian jumping worm, crazy worm, crazy snake worm, snake worm, Alabama jumper

Description:

Jumping worm (Amynthas agrestis) is an invasive earthworm from East Asia, one of several closely related "jumping worms" now spreading across North America [1][2]. It earns its name from its wild behavior: when picked up it thrashes, wriggles like a snake, and can even spring off the ground [1]. MISIN tracks it because it strips the leaf litter from forest floors and turns rich topsoil into loose, grainy castings, harming native plants, gardens, and the wildlife that depend on healthy soil [1][2].

Identification:

Jumping worms look much like ordinary earthworms at first glance ? smooth, glossy, gray to brown, and 1.5 to 8 inches long ? but two things set them apart [1][2]. First is the band (clitellum) near the head: on a jumping worm it is milky-white to gray, smooth, and flat against the body, encircling it completely, rather than the raised, pinkish, saddle-shaped band of common European earthworms [1][2]. Second is the behavior: handle one and it thrashes violently, slithers like a snake, and may even drop its tail to escape [1]. A third clue is in the soil ? jumping worms turn the surface into a uniform, grainy layer that looks like coffee grounds [1].

Jumping worms are easiest to find and identify from mid-to-late summer into fall, when they reach full size and their telltale white band is clearest; the worms themselves die off after the first hard frost [2]. Look in the top inch or two of soil, in leaf litter, and under mulch, and watch for that coffee-ground soil texture [1].

At-a-glance cues:

1. Thrashes, wriggles like a snake, or springs off the ground when handled, and may shed its tail [1]
2. Smooth, milky-white band (clitellum) that is flat against the body and rings it completely, near the head [1][2]
3. Smooth, glossy gray-to-brown body, 1.5 to 8 inches long [1][2]
4. Loose, grainy surface soil that looks like coffee grounds [1]

Habitat:

Jumping worms live in the top layer of the soil and in leaf litter, where they feed on dead leaves and organic matter [1][2]. They turn up in forests, gardens, lawns, mulch piles, and landscaped beds, and they tolerate a wide range of conditions, which helps them spread [1]. Unlike deeper-burrowing earthworms, they stay near the surface, so their effects on the leaf layer and topsoil are quick and obvious [2].

Jumping worms are native to East Asia, including Japan and Korea [1]. In North America they are introduced and invasive, and they have spread widely in the eastern and midwestern United States, largely by moving in soil, mulch, and potted plants [1][2]. The adult worms cannot survive cold winters, but their egg cases (cocoons) can, so the worms return each spring even in cold climates [2].

Reproduction:

Jumping worms spread mostly as tiny egg cases called cocoons ? about the size of a mustard seed, soil-colored, and easy to miss [2]. These cocoons ride along in soil, mulch, compost, potted nursery plants, and sod, and on shoes, tools, and tires, which is how the worms reach new yards and woods [1][2]. They also spread when people dump fishing bait (jumping worms are sometimes sold as "Alabama jumpers") or share worm-laden compost or plants [1][2]. Because each worm can reproduce on its own without a mate (a process called parthenogenesis), even a single worm or one cocoon can start a new population [1][2].

Their life cycle is yearly and matters for control. Adults die with the first hard frost, the cocoons survive winter in the soil, the young hatch in spring, and the worms mature by mid-to-late summer [2]. The best time to find and remove adults, and to avoid moving infested soil, is late summer and fall ? before the cocoons are spread to new ground [1][2].

Impact and Damage:

Jumping worms are not harmful to people or pets ? they do not bite or carry disease [1]. The harm is to soil, plants, and gardens. As they feed, they quickly strip away the leaf litter and the rich upper soil and leave behind loose, grainy castings that look like coffee grounds [1][2]. This soil holds water and nutrients poorly, erodes easily, and can leave garden plants, lawns, and tree roots struggling in what looks like loose grounds rather than firm earth [1][2].

In natural areas the damage is more serious. By eating the leaf-litter layer of the forest floor, jumping worms remove the seedbed and cover that native wildflowers and tree seedlings need, and they take away the home and food of the insects, salamanders, and ground-feeding birds that depend on leaf litter [1][2]. The change in the soil can also make it easier for other invasive plants to move in [2]. There is no known way to control invasive earthworms over large areas, so keeping them from spreading is the main defense [1].

Similar species:

Common earthworms and nightcrawlers (European Lumbricus and related species) are the most likely confusion, since they share the same size and color. You can tell them apart by the band and the behavior: a common earthworm's band is raised, pinkish, and saddle-shaped, and the worm moves slowly, while a jumping worm's band is smooth, milky-white, and flat against the body, and the worm thrashes and snakes wildly when handled.

Other jumping worm species (such as Amynthas tokioensis and Metaphire hilgendorfi) are close relatives that look and behave the same and often live together in the same soil. They can only be told apart from Amynthas agrestis by close examination, and they are invasive and managed the same way, so for control they can be treated as the same problem.

Monitoring and rapid response:

Signs to watch for:

1. Worms that thrash, snake, or jump when handled and may drop their tails ? most active and full-sized in mid-to-late summer and fall [1][2]
2. A smooth, milky-white band flat against the body near the head [1][2]
3. Loose, grainy surface soil that looks like coffee grounds [1]

What you can do:

1. Learn to recognize jumping worms, and check your soil for the coffee-ground texture, especially in late summer [1].
2. If you find them, hand-collect the worms and throw them away sealed in a bag in the trash ? never use them as fishing bait or compost worms, and never release them [1][2].
3. Do not move soil, mulch, compost, or plants from an area that has jumping worms; buy bare-root plants when you can, or knock the soil off potted plants and inspect it, and use compost or mulch that has been heat-treated to kill cocoons [1][2].
4. Clean soil off your shoes, tools, tires, and equipment before leaving an infested area, since the cocoons travel in that soil [1][2].
5. Natural area crews and gardeners moving plants or soil should follow clean-equipment practices and avoid sharing soil, mulch, or plants from infested sites, since there is no large-scale way to remove established worms [1][2].

When to call a professional:

1. Large infestations, or questions about managing them in a garden, nursery, or natural area ? contact your local cooperative extension office or state invasive-species program for current guidance [1][2].
2. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. Minnesota Department of Natural Resources. Jumping Worm (Amynthas species). dnr.state.mn.us
2. University of Massachusetts Amherst, Center for Agriculture, Food, and the Environment. Jumping/Crazy/Snake Worms (Amynthas spp.). umass.edu
3. North Central IPM Center. Jumping Worms ? Pest Alert. ncipmc.org

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