This article by Pat Foley first appeared our publication WildforaRI, Spring 2022
What are they?
Members of the species Amynthas agrestis, Amynthas tokioensis, and Metophire hilgendorfi have been colloquially called Asian Jumping Worms. Other common references are: Georgia or Alabama Jumper, Jersey Wriggler, Crazy Snake-Worm and Wood Eel.
They range in size based on age and environment but four to five inches long seems a typical adult size, so within the size range of other species referred to as “earthworms.” The so-called “jumping worms” are primarily distinguishable by their very vigorous flailing when disturbed. Undisturbed, they move side-to-side, with a snakelike motion.
Why are they a concern?
Earthworms, generally, have been considered beneficial to gardens because they break down decaying organic matter and make it available as plant nutrition. However, there have been no earthworms native to northeastern forests since the last ice age, according to studies. Since current northeastern forest biology evolved without earthworms, all present species cause some damage, by consuming the duff layer of the forest floor.
The jumping worms are particularly destructive because of their high reproduction rates, ability to live in very dense clusters, voracious appetites, and large dry castings that are inhospitable to plants and soil organisms.
How did they get to Rhode Island?
Worms of these Asian species originated in Japan and Korea. Documented sightings in American nurseries and arboreta date to the late 19th century and available studies speculate their introduction dates to the earliest shipments of ornamental plants from those countries in the latter 1800s.
Despite their prolific reproduction, no definitive scientific evidence accounts for their relatively recent emergence as an invasive of concern. Speculation suggests a warming climate, continued trade in ornamental plants from host countries, internet shipping of the worms for use as bait in sport fishing, and the very portable nature of the tiny cocoons that overwinter through extremely cold temperatures.
Approximately half the United States has identified or is soon likely to identify infestations. Early infestations, particularly in southeastern states have spread northward and westward.
How to locate and control them?
The RI Department of Environmental Management has no policy concerning the control of jumping worms. “Unfortunately, it’s not one of the priority pests we look for, and we have no authority to do anything about them,” said Cynthia Kwolek, a senior environmental planner in the Cooperative Agricultural Pest Survey (CAPS), which monitors introduced pests in the state.
“They do seem pretty destructive,” she said. “People are calling to say they have jumping worms in mulch that they’ve purchased.”
So, gardeners need to practice their own diligence in identifying them. Jumping worms, once established— which might only require a season or two—give strong evidence of their presence:
• They appear to not burrow like other earthworms, but live in leaf litter, compost, and under stones and plant pots
• They are often found in large groups
• Their vigorous movements easily distinguish them from other earthworms
• Close examination reveals several distinctive physical characteristics related to color and the placement and appearance of the clitellum band
• Soil in infested areas is very grainy and coarse, described as ground taco meat or Grape Nuts cereal in appearance.
• Affected forests lose native flowers and young saplings and are dominated by Jack-in-the-pulpit, ferns and grasses, plants not harmed by jumping worm activity.
Can we stop them?
Jumping worms are subject to predator control in their native range, but introducing those organisms here likely would entail other risks and outcomes
Currently, no definitive prevention or management program exists, but there are steps we can take to reduce damage and delay the worms’ spread. A Cornell University Extension program offers this advice:
• Do not buy or use jumping worms for bait, vermicomposting, or gardening.
• When purchasing bulk mulch or compost, use a reputable producer that has heat-treated the material to a temperature of 130°F for at least three days to destroy the cocoons or purchase bagged mulch.
• Check your property for jumping earthworms using a mustard pour (it won’t harm your plants). Mix a gallon of water with 1/3 cup of ground yellow mustard seed and pour slowly into the soil. This will drive any worms to the surface where you can easily remove them.
• Cocoons are sensitive to heat and can be destroyed with clear plastic solarization; in late spring or summer, cover moistened soil with a sheet of transparent polyethylene for two to three weeks or until the soil temperature exceeds 104°F for at least three days.
• Be careful when sharing and moving plants; always check for worms and know where your plantings come from; buy bare root stock when possible.
• If you have a small population of jumping worms, handpick and destroy them by bagging them and throwing them in the trash, or place them in a bag and leave out in the sun for at least 10 minutes; then throw the bag away.
• Research is currently being conducted on invasive worms at the University of Wisconsin and several practices do show some promise of control. Abrasive materials such as biochar (ground up charcoal) and diatomaceous earth (fossilized diatoms) may kill adult jumping worms. Incorporate one of these products into the infested soil to a depth where the worms are located.
What else should I know?
RIWPS is developing a policy and procedures for safeguarding the plants we sell. Volunteers will be educated about the worms—their appearance and life cycle. Any plants dug from the ground will have their roots cleaned and be potted in sterile potting soil. These practices should minimize the chance of spread.
There is very useful information online from federal, state and local government sources; partnerships; and councils or task forces. Some are cited below:
USDA National Invasive Species Information Center: https://www.invasivespeciesinfo.gov/terrestrial/invertebrates/asian-jumping-worm
National Park Service Northeast Temperate Network Inventory & Monitoring Program: https://irma.nps.gov/DataStore/DownloadFile/603161
Connecticut Agricultural Experiment Station: https://portal.ct.gov/-/media/CAES/DOCUMENTS/Publications/Fact_Sheets/Entomology/Jumping-worms-in-Connecticut.pdf
UMass Extension Landscape, Nursery and Urban Forestry Program: https://ag.umass.edu/landscape/fact-sheets/jumpingcrazysnake-worms-amynthas-spp
Cornell Cooperative Extension: http://warren.cce.cornell.edu/gardening-landscape/warren-county-master-gardener-articles/invasive-asian-jumping-earthworms
Jumping Worm Outreach, Research & Management Working Group: https://www.wnyprism.org/wp-content/uploads/2021/05/JWORM-Homeowner-Guide-Jumping-Worms-Accessible-Version-2021.pdf
Partnership for Regional Invasive Species Management: https://www.wnyprism.org/invasive_species/jumping-worms/