By Silvia Strobl, Master Gardener in Training
At the 2024 Master Gardeners of Ontario Conference I had a chance to hear Dr. Michael McTavish, Ontario’s foremost expert on earthworms, speak about invasive jumping worms. First reported in southwestern Ontario in 2014, Ontario now has four species of these pheretemoid (litter dwelling) Asian worms. They’ve been observed as far north as Ottawa and their populations are growing at an alarming rate. In the USA, research on biocontrols is ongoing, but currently there are no registered pesticide options for either gardeners or land managers. Prevention is the only strategy.
Dr. McTavish’s message resonated with me. My conference roommate, a Master Gardener from Hamilton, has been dealing with them for two years. Her garden is one of the 44 confirmed jumping worm locations in Ontario (Figure 1). Since I visit Hamilton monthly to help in my mother’s garden, we both need to take precautions to avoid introducing this pest not only to mom’s Hamilton garden but also mine north of Peterborough.
Figure 1: Jumping worms have been reported to EDDMaps in the following Ontario jurisdictions: Lambton County (1), Niagara (2), Hamilton (12), Brant (1), Waterloo (1), Wellington (1), Halton (3), Peel (4), Dufferin (1), Simcoe (1), Toronto (14), York (1), Lennox & Addington (1), Lanark (1), but this is an under count since not everyone reports sightings (EDDMaps accessed April 29, 2024). For example, another Master Gardener, located in Ottawa, has found them in that jurisdiction.
In gardens, jumping worms quickly consume organic matter in the upper soil layer resulting in soil drying, erosion, loss of nutrients, and ultimately decreased plant growth. In forests, jumping worms rapidly consume the leaf litter disrupting nutrient cycles, preventing seed germination, decreasing biodiversity, damaging the soil biome, and degrading habitat. To learn more about the impacts, view this video by one of America’s leading researchers on jumping worms, Dr. Brad Herrick from the University of Wisconsin Madison Arboretum:
In the US jumping worms have been expanding their range since 1951, but in Ontario we still have opportunities to avoid introducing this pest to our gardens. Dr. McTavish identified three actions for gardeners.
- Learn to identify jumping worms
Look for these three things in your garden or any natural area you frequent regularly:
- Loose, dry, crumbly worm casts in layers, not piles. Casts look like coffee grounds or ground beef and layers can be up to 10–15 cm thick (Figure 2, below).
Figure 2: Photo Credit, Michael McTavish.
- Worms in the casting layer that thrash about wildly when disturbed
- Adult worms with a milky white ring that completely encircles the worm fairly close (14 segments) to the head (Figure 3, below). As well, the skin has a distinctive glassy sheen, the body has a snappy, turgid feel when grasped, and the tail may detach when the worm is threatened. The clitellum is the reproductive structure where the cocoons are stored and secreted.
Figure 3: Photo Credit, Bev Wagar.
Cocoons hatch in May when soil temperatures are consistently 10oC. The juvenile worms don’t have the identifying white ring until about 60 days later in the summer when they become adults. At that time they reproduce asexually (parthenogenetic), and a single worm can produce several dozen egg cases (cocoons) in one season. Cocoons are small and indistinguishable from dirt, hence easily transported on our shoes, tools and when moving infested plant roots and compost (Figure 4, below). The adult worms die in late fall when the soil freezes, but the cocoons survive the winter.
Figure 4: Photo credit, Marie Johnston, UW-Madison Arboretum https://dnr.wisconsin.gov/topic/Invasives/fact/jumpingWorm).
The best time to identify jumping worms is at the adult stage in summer and fall.
- Report observations to EDDMaps
Most of the confirmed jumping worm records in Ontario are from gardens, but they have also been found on trails and in parks. If you do see one, report your sighting by taking and uploading a photo taken with your smartphone to EDDMaps. You can choose a privacy option to obscure the exact geographical location as has been done for most of the records in EDDMaps to date. There are several official verifiers, including Dr. McTavish, and distribution information contributed by citizen scientists will motivate further research on control of this invasive species.
- Use best practices to slow the spread
Practicing sanitation and dedicating tools and shoes for work only in known infested areas and not moving soil, plants and compost will limit spread of jumping worms. If you do have jumping worms you can still do a lot to slow the spread to other areas, and the following practices can also substantially decrease the likelihood that they won’t invade your garden in the first place.
- Inspect any new plant, soils and mulch materials, including bagged leaves, coming into your garden. If you find jumping worms, put them in a jar filled with vinegar or isopropyl alcohol or a ziploc bag. Do not put them in the compost or throw them away.
- Ideally, make your own mulch and compost on your own property. In New York State Jumping Worms spread was traced to wood chip mulch piles made from the 15,000 trees downed in Hurricane Sandy that were moved to different parks (Dobson 2024).
- If exchanging plants, swish plant roots and gently massage the roots to remove most of the soil in first one bucket of lukewarm water and then if more soil is present, another bucket. Inspect the roots for cocoons which are visible to the human eye when not obstructed by soil. Let soil settle in the buckets for a couple of days before carefully draining the water and then solarize the soil (Görres 2024).
- If you do bring in bulk soil, compost or mulch, solarize it by spreading it 15 to 20 centimetres thick on dry cardboard over a length of 3 to 4.5 metres and cover it with translucent painter’s plastic drop cloth (6 mil thick). Let it sit for 72 hours and get to more than 40oC which will kill worms and cocoons as these don’t survive temperatures over 40oC (Johnston and Herrick 2019).
- Get in the habit of cleaning the soles of your shoes or boots before and after hiking in natural areas or visiting or working in other gardens. Not only will this help avoid spreading jumping worm cocoons, it will also help avoid spreading seeds of invasive plants.
Anything we do now to prevent or slow the spread of jumping worms gives researchers time to do studies to identify control options and seek regulatory approvals. It might also give native plants and wildlife time to adapt to yet another forest pest.
I left Hamilton last week after washing my garden shoes, gardening clothes, and Hori-Hori garden knife. I also showed my mother the video at the above link and, given the incidence of jumping worms in Hamilton, asked her not to accept any plants from other gardens.
What will you do differently to mitigate the possibility of bringing jumping worms into your garden?
References
Dobson, Annise. 2024. Jumping Worms: What you need to know, and how you can help prevent their spread. https://youtu.be/3qneehkTz_w?si=zTQcchMzzOTSEE3t
Görres, Josef. 2024. Spread, Impact and Control of Jumping Worms. Presentation to University of Rhode Island Master Gardener Program. https://youtu.be/rtb4ffRNCS4
Herrick, Brad. 2020. Invasive Jumping Worms. https://youtu.be/8CPQH8q1Pfc?si=7dyrzNXFl91np7BI
Johnson, M.R. and B.M. Herrick. 2019. Cocoon Heat Tolerance of Pheretimoid Earthworms Amynthas tokioensis and Amynthas agrestis. The American Midland Naturalist Vol. 181, No. 2, pp. 299-309. https://www.jstor.org/stable/45434119?read-now=1#page_scan_tab_contents
McTavish, M. 2022. Jumping worms–white-collared invaders spreading in southern Ontario. https://www.invasivespeciescentre.ca/wp-content/uploads/2022/03/JumpingWormIDGuide_2022-02-17.pdf
Resources
McTavish, M. 2023. ATTENTION: Invasive jumping worms in Ontario. Factsheet.
Related
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