Why are Jumping Worms a Concern?
While many people think of earthworms as "garden helpers," Jumping Worms (Amynthas spp.) are different. They are aggressive ecosystem disruptors that change the very chemistry and structure of our soil. In Ontario, they pose a serious threat to our forests, gardens, and local biodiversity.
1. They Strip the Forest "Blanket"
Native forests rely on a thick layer of decomposing leaves and organic matter called the duff layer. This layer acts as a nursery for tree seedlings, wildflowers, and ground-nesting birds. Jumping Worms are voracious surface-feeders; they can consume an entire season's worth of leaf litter in just a few months, leaving the soil bare and unprotected.
2. They Create "Coffee Ground" Soil
One of the easiest ways to identify an infestation is by the soil texture. Jumping Worms turn rich, stable soil into loose, grainy castings that look like spent coffee grounds. This creates two major problems:
Erosion: This loose soil washes away easily during heavy rains, sending sediment into our waterways.
Drought Stress: The soil can no longer hold moisture or nutrients, causing the roots of native plants and garden perennials to dry out and die.
3. They Spread "Invisibly"
The biggest concern for trail users and gardeners is how easily they travel. A single Jumping Worm can produce cocoons (eggs) without a mate. These cocoons are:
Microscopic: Only 1–3 mm in size (the size of a mustard seed).
Resilient: They can survive harsh Ontario winters and extreme drought.
Sticky: They cling to the mud in your boot treads or the tires of your bike, meaning you can accidentally start an infestation in a new forest without ever seeing a live worm.
4. Impact on Ontario’s Biodiversity
When Jumping Worms move in, native species move out. By destroying the soil structure, they threaten:
Sugar Maples & Trilliums: Seedlings cannot take root in "coffee ground" soil.
Ground-Nesting Species: Birds and salamanders lose their habitat and food sources.
Carbon Sequestration: As they rapidly break down organic matter, they release stored carbon back into the atmosphere as CO2.
References
Exotic Asian pheretimoid earthworms (Amynthas spp., Metaphire spp.): Potential for colonisation of south-eastern Canada and effects on forest ecosystems
Invasive Jumping Worms Damage U.S. Soil and Threaten Forests
Invasive Jumping Worms: The Impact of a New Soil Invader https://franklin.osu.edu/sites/franklin/files/imce/Program_Pages/ANR/Invasive%20Jumping%20Worms%20The%20Impact%20of%20a%20New%20Soil%20Invader%2012.1.2020.pdf
Jumping worms unearth problems for forest ecosystems
https://blog.invasive-species.org/2022/12/02/jumping-worms-unearth-problems-for-forest-ecosystems/
All About Invasive Jumping Worms https://conservationhamilton.ca/blog/all-about-invasive-jumping-worms/
Invasive Species Centre: Jumping Worms