Submitted by Bev Wagar, Master Gardener

Jumping worms arrived in southern Ontario at least a decade ago and, since 2019, they’ve been writhing and chomping through gardens and naturalized areas in Toronto, Burlington, Dundas, and Hamilton—including the North End. Unlike the familiar wigglers and crawlers, these weird, invasive, snake-like worms thrash wildly when disturbed. Despite being surface dwellers that die in the winter, they are formidable ecosystem engineers. Eating all available organic matter (mainly leaves and seeds but also wood mulch and peat) they transform the topmost soil layer into dry, granular castings that damage the soil’s chemistry, biology, and structure. Forests and gardens can no longer support seedlings, mychorrizal networks, and the soil food web. Understandably, gardeners are afraid.

Identification Up to seven inches in length at maturity, with a light-coloured band that completely encircles the worm near its head. Other features include: skin with an iridescent sheen; thrashing behaviour; and a snappy almost “muscular” feel when held between the fingers. It may shed its tail when threatened. For a positive identification, take several good photos and report the observation to iNaturalist (https://www.inaturalist.org ). Then kill the worm by dropping it into a tub of vinegar or isopropyl alcohol. Do not put jumping worms in the compost or throw them away.

Life Cycle Jumping worm eggs overwinter in the soil. Hatching starts in late spring when temperatures are consistently above 10C. By about mid-June, worms are large enough to identify. About 60 days after hatching, they begin depositing egg cases—researchers estimate about four per week. To check for their presence, poke the soil with something like a barbeque skewer or screwdriver. Another way to bring them to the surface is with a mixture of powdered mustard and water (information here: https://extension.umd.edu/resource/invasive-jumping-worms/ . The mustard will not harm the soil, your plants, or the worms.

There are no registered pesticides for jumping worm control. Potential predators include snakes, centipedes, moles, gophers, skunks, opossums, and racoons but we don’t know whether they will develop a taste for this new food source. Heat will kill both eggs and worms but more research is needed to clarify the required temperature and duration. The best strategy is prevention.

Reduce the risk Jumping worms reproduce without mating so it only takes one worm, or egg, to start a new infestation. The tiny (1 to 2 mm) eggs can hitchhike in soil stuck to boots, tools, and tires. Both worms and eggs can arrive in bulk soil amendments such as woodchips and mulch as well as purchased plants. Gardeners, often unaware that they have jumping worms, may donate “dug” plants to neighbourhood plant sales or swaps.  Root-washing and re-potting dug plants can reduce, but not eliminate, the risk.

Tips:

  • Do not share plants. Neither give nor take. Gardeners often are unaware that they have jumping worms.
  • Ask garden center staff about how they are dealing with jumping worms.
  • Use native plants. Most are better able to withstand infestations.
  • Grow your own plants from seed. Use sterile potting mix.
  • Before planting, wash off all soil or potting mix from roots.
  • Provide shoe covers for garden visitors.
  • Clean shoes and tools when leaving an infested area