Invasive Jumping Worms

• By Cathy Caldwell
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• January 2023-Vol.9, No.1
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• 5 Comments

By now you’ve probably heard about the latest invasive species, a type of earthworm that goes by many names, including jumping worm, crazy worm, snake worm, Asian jumping worm, crazy jumping worm  — we’re just getting started here — Jersey wigglers, Georgia jumpers, and Alabama jumpers.  Some of these names may seem inappropriate, but most of these worms DO thrash about and often move like snakes (to see them move, see the video at wisconsin.gov).  While this behavior is not grounds for concern, there are important ecological reasons for us all to be on the lookout for them in our yards and gardens.  And yes, jumping worms have been found in Virginia.  See WSLS.com/Destructive jumping worms spotted throughout Virginia.

These invasive worms actually change the composition of the soil — for the worse.  How do they do this?  By eating such large quantities of the organic matter in the soil that the nutrients needed by plants and wildlife are depleted.   Jumping worms tend to stay in the leaf litter or in the upper few inches of the soil, and they gorge themselves in both areas. They also alter the soil structure, leaving it gravelly, drier, and less hospitable to microorganisms like fungi and bacteria.  Unlike the earthworms we’re familiar with, these jumping worms stay very near the surface, so they provide no beneficial aeration, nutrient movement, or water infiltration.  In addition, the worm castings (feces) sit on top of the soil, leaving their nutrients out of reach of plant roots, and increasing the risk of nutrient runoff.

Most organisms that rely on the normal composition of the forest floor for food or habitat will probably be adversely impacted by invasive jumping worms — including plants, insects, birds, and other animals, though there are exceptions, most notably, poison ivy, which is apparently unaffected by the changes wrought by jumping worms.  But for most plants, a forest floor depleted of its normal top layer is less hospitable for seed germination and plant growth. The heavy feeding of jumping worms on leaf litter can expose the root systems of trees and reduce the fertility of our gardens.  Plant communities may be altered by the reduced survival of newly-sprouted plants, resulting in diminished native biodiversity in forest ecosystems. The threats posed by these jumping worms demand our attention.

So what exactly is a crazy jumping worm and how do you identify one?  The jumping worms are three similar-looking species: Amynthas tokioensis, Amynthas agrestis, and Metaphire hilgendorfi, all of which are in the family Megascolecidae. They are all non-native species, originating from Asia.  But here’s a surprise:  those earthworms we love to find our in our gardens are apparently not natives either; they are of European or Eurasian origin.  Exactly how and when jumping worms arrived in the United States remains unclear, though scientists believe that nursery stock from Asia was the likely source.  In any event, these worms have now spread into much of the Eastern half of the country.

Note the pale clitellum on this jumping worm. Photo: Dr. Matt Bertone, NC State Dept. of Entomology & Plant Pathology

The main identifying feature of a jumping worm is its clitellum. The jumping earthworms have a clitellum that is circular and goes all the way around the body. In the other earthworms we’re accustomed to, the clitellum goes only halfway around the worm and may be saddle-shaped.  The  clitellum of jumping worms is pale in color, and is smooth and flush with the rest of the body.  In other earthworms, the clitellum is a thickened swelling that is reddish-pink or orange, may be ridged instead of smooth, and may bulge out from the rest of the body. One final difference:  in jumping worms, the clitellum is closer to the worm’s head than is the case with other earthworms.

Note the orange-ish color and heightened profile of the clitellum on this common earthworm (Lumbricus terrestris). Photo: Joseph Berger, Bugwood.org

In all species of earthworms, the clitellum secretes a small mucus “cocoon” that encapsulates the eggs. These spherical cocoons, about the size of a mustard seed, protect the egg over winter. Jumping worms are believed to have a single generation each year, with the eggs hatching in the spring, and the worms reaching adulthood by summer, when they lay their eggs and then die during winter. Amynthas spp. are asexual and do not require a mate to reproduce.

According to Dr. Matt Bertone, not all species of jumping worms “flail about in response to being disturbed. Also some other types of worms behave erratically when touched or approached. Thus the jumping behavior is not always the best way to identify these earthworms.”   So we all need to brush up on our clitellum-identifying skills, and then share our expertise with neighbors, friends, and fellow gardeners.

Castings, resembling coffee grounds, surround this tree, whose roots have been exposed by jumping worms. Photo: Robert Lee, Bugwood.org

A telltale sign of a jumping worm invasion is bare soil covered with their castings, which look like dried coffee grounds.  If you observe this phenomenon, you will want to confirm your suspicions.  Mature adult jumping worms are usually visible in late summer, but if you’re not seeing any, you can treat the suspicious area with a mixture of  one gallon of water and 1/3 cup of ground yellow mustard seed.  Pour the mustard solution slowly over the area. If there are jumping worms in that location, they will be irritated and brought to the surface, where they can be collected for identification. Note: this is not a means of managing these earthworms — it does not kill them — but merely a detection method.

Currently there is no pesticide known to control jumping worms. But Dr. Joseph Görres, associate professor in the Plant & Soil Science Department at the University of Vermont, is currently researching the use of reduced-risk, biological pesticides to manage jumping worms. Unfortunately, he reports that there is inadequate research funding available from federal and state agencies.

If you do find jumping worms on your property, remove and dispose of them to the maximum extent possible.  Proper disposal methods for jumping worms include:

• placing the worms in a plastic bag and leaving it in the direct sun for at least 10 minutes before disposing of the bag in the trash, or
• drowning the worms in a container of soapy water deep enough that they cannot climb out of it. Make certain all worms are thoroughly dead before dumping the water and worms out.

Please report your find to your local Cooperative Extension office.  Taking photos of the worm would be very helpful, especially if the clitellum can be clearly seen on the worm. Also helpful: a short video clip of the worm’s behavior.  If you can collect a specimen, place it in rubbing alcohol and submit it to your local Cooperative Extension Office for identification and confirmation. Specimens can be placed in a small bottle, jar, container, or a resealable plastic bag. The worm should be submerged completely in the rubbing alcohol to preserve it until it can be seen by an expert. The Extension Office for Albemarle/Charlottesville is in the County Building on Fifth Street Extended (434-872-4580), and the Horticultural Help Desk can be reached at (434) 872-4583 or albemarlevcehelpdesk@gmail.com.

Since the cocoons and eggs survive the winter, they are a key to some kind of control.  You may be able to kill the cocoons/eggs with solarization; recent research suggests that heating the cocoons of jumping worms to somewhere around 104°F for at least 3 days will kill the cocoons.  Read more about solarization at Univ. California/Soil Solarization for Gardens & Landscapes.

Jumping worms and their cocoons/eggs can be spread via mulch, compost, nursery stock, transplanting, and fishing bait.  Some jumping worms have apparently been sold for bait, and experts suspect that jumping worms may have been released in some areas for this purpose.  Nursery plants are believed to have been a major mode of travel for jumping worms.  In fact, nursery plants are believed to have been the source for the jumping worms that have invaded the garden of a fellow Master Gardener.  To help prevent further spread, scientists urge us to exercise caution in buying or sharing plants.

Concern about the impact of jumping worms is growing; in fact, a two-day Jumping Worms Conference hosted by the University of Massachusetts Extension in January of 2022 drew over 700 people. The conference generated an online list of Jumping Worm Frequently Asked Questions & Answers that is well worth reading.   A major worry is the impact of jumping worms on our forests. Unless and until a viable treatment is available, we all need to pitch in to help prevent the spread of jumping worms, and there are indeed effective measures we can take.

How to Prevent the Spread of Jumping Worms

• Be cautious when sharing potted plants. Share bare root plants when possible.  Of course, if you have jumping worms on your property, you should NOT be sharing any plants at all.
•  Do not buy jumping worms for fishing bait or for vermicomposting. Do not dispose of unused baits in the environment.
• Be cautious when purchasing containerized plants; look closely at the soil and under the pot for worm castings.   Bare root plants are a better choice.  Or turn a potted plant into bare root by washing all soil off the roots and disposing of wash debris carefully.
•  Shop with local businesses that take steps to prevent the spread of jumping worms.
• Make your own compost on your property.
• If you must buy mulch or compost, be aware that if these materials attain proper, high temperatures for the right amount of time (104-130°F for a minimum of 3 days) the heat can kill cocoons, reducing the risk of them coming in on such materials.  Make inquiries of your mulch or compost supplier.
• If you have to buy compost or mulch, solarize it after delivery, or alternatively, buy it in bags. Solarize mulches and compost by sandwiching it between translucent plastic sheets. The bottom sheet will prevent the worms from moving into the soil. The top sheet will cause the pile to heat up.  Detailed directions for solarization:  Univ. California/Soil Solarization for Gardens & Landscapes.
• Clean soil from shoes, tools, vehicles, etc. that are being moved from one area to another, especially if the area of origin has jumping worms present.

“Remember, if it has soil, it can have jumping worms!”  So says Dr. Matt Bertone, the director of the Plant Disease and Insect Clinic at North Carolina State University.  Advice well worth remembering.

SOURCES:

“Jumping Worms (Amynthas spp.),” Va.Coop.Ext./ENTO-427

Video:  Va.Coop.Ext/Fairfax County/Bug of the Week: Asian Jumping Worm

“Jumping/Crazy/Snake Worms – Amynthas spp.,” University of Massachusetts Extension (helpful identification chart and photos)

“Jumping Worms,” NC State Ext./Jumping Worms

“Invasive Worms, University of Vermont Entomology Research Laboratory

Jumping Worms Working Group/New York Invasive Species Research Institute

Video:  video.cornell.edu/State of the Science: Jumping Worm Research & the JWORM Working Group

Virginia Cooperative Extension – Albemarle Office
5th Street Albemarle County Office Building, 2nd floor
460 Stagecoach Road, Charlottesville VA 2290