By Paige Boyle
Earthworms can be found throughout Minnesota lawns and gardens, and earthworm presence and activity is generally considered beneficial. In fact, many home gardeners go to great lengths to promote earthworm activity in their yards. As we enter the fall lawn care season, there is one problematic group of earthworms to keep an eye out for, though: Jumping worms.
What are jumping worms?
Jumping worms are a group of non-native earthworms from the Amynthas and/or Metaphire genera that have been found throughout central and southern MN (Figure 1). As of July 1, 2024, jumping worms are on Minnesota’s list of prohibited invasive species, meaning it is a misdemeanor to possess, import, purchase, transport, or introduce jumping worms without proper permitting. This is largely due to their ability to destroy soil structure and disrupt nutrient cycling. Generally, jumping worms within residential yards prefer garden beds, where they can damage or kill ornamental plants, but they can spill over into garden-adjacent lawns as well, where they may damage turf directly or where their casts (waste) may smother turf. Jumping worms may also spread into the ecosystem beyond the home yard, where they can cause significant damage to forest ecosystems in particular.
How can you help slow the spread of jumping worms?
First, learn to identify them. The most noticeable feature of jumping worms is the characteristic snake-like thrashing they exhibit when disturbed. Sometimes this is so intense that their tails will fly off their bodies. Another key feature includes a milky pink or gray ring around their bodies, which, unlike many other earthworms, isn’t raised up, but is flush with the rest of the body. You’ll also likely notice their casts which look like used coffee grounds rather than the piles of pellets commonly excreted from other earthworms. These may be present in garden beds or above or within the turfgrass plant canopy.
If you do see jumping worms in your yard, capture them, snap a photo, report your suspected jumping worm sighting to the MN Department of Natural Resources, and throw them in the trash. Don’t move them throughout the yard. To prevent the spread of jumping worms, make sure to buy your compost and mulch from reputable dealers who follow pathogen-reduction practices, clean your lawn care and gardening tools regularly, and inspect any new plants and sod for coffee-ground-like casts before purchasing or buy bare-root if possible. Don’t purchase or accept plants from a location with a known jumping worm presence. If you’re purchasing earthworms for composting or fishing bait, never purchase worms labeled as snake worms, Alabama jumpers, or crazy worms, and never dispose of unused worms, regardless of species, in the environment. Instead, throw unused worms in the trash.
Join the Jumping Worm Bioblitz September – October 2024.
To learn more about jumping worms, visit the MN Department of Natural Resources jumping worm profile and UMN Extension’s fact sheet on jumping worms.