Jumping worms: What do farmers need to know?

Author: Angela Gupta, UMN Extension Educator, Forestry

Jumping worms, Amynthas spp., are a genus of invasive earthworms new to Minnesota. Farmers should learn about jumping worms and the conditions that allow them to spread in order to prevent jumping worms from coming on to their farms. These worms are most noticeable when they reach full size in late July or early August, but prevention activities are important throughout the year. Currently there are no scientifically recommended management options for jumping worms so prevention is the only clear choice.

Jumping worm basics

Jumping worms are a major problem for gardeners and potentially farmers because they live in the top few inches of soil and vigorously consume many types of organic matter in that top soil horizon, including plant roots. There are no native earthworms in Minnesota and invasive earthworms have long been a problem in Minnesota’s forests, but jumping worms create additional problems. The normal suite of non-native Eurasian worms commonly found in Minnesota inhabit the soil from 0-6 feet in depth. However jumping worms are found in only the top few inches of soil. After jumping worms move into a site all other earthworms seem to disappear, we’re not sure why. However, after the arrival of jumping worms, the total density of worms may double, meaning that in a 1 square surface meter of earth where there might have been 50 Eurasian worms before jumping worms invaded there may be 100 or more jumping worms all in the top few inches of soil. Jumping worms are eating, living, reproducing, and defecating in that top soil layer which is what causes the trouble.

Photo: David Bierman

Most growers first notice these very active and abundant adult jumping worms in August or September. These worms vigorously wiggle in a snake-like movement and can lose their tails when aggravated. Some gardeners notice coffee-ground-textured soil that is the casting (worm poop). The texture of the casting is very noticeable and increases soil erosion. Gardeners also report their plants, commonly shallow rooted plants like hostas, are either doing poorly or actually die. Jumping worms have also been found borrowing into plant roots and eating them. Most of the impacts we’ve seen so far are in gardens on ornamental plants, so we do not yet have a good sense of how jumping worms might impact vegetable crops. 

The following video highlights the unique movements of jumping worm:

The entire jumping worm life cycle happens in the top soil horizon, so accidentally spreading jumping worms or their inconspicuous egg cases (called cocoons) is very easy. Jumping worms, as their name implies, are very active. When distrubed they wiggle and move quickly. Adults lay cocoons which harbor their eggs. Cocoons are spheres with a diameter of 1-3 mm, can be golden to dark black in color, and can be very hard to distinguish from soil. They can resemble poppy seeds. We believe jumping worms can lay several sets of cocoons during our growing season and that adults likely die when they freeze in the fall. The cocoons and eggs overwinter in the soil and can be moved when folks manage their autumn leaves. Both eggs and worms can be moved in contaminated soil, plant roots, wood mulch and compost.

Jumping worms are very unusual in that they can survive in mulched wood. They can survive in mulch and compost from sites that haven’t followed the “process for further reducing pathogens” to reach needed temperatures to kill the worms and their eggs. Jumping worms and their eggs can also survive in store-bought bagged wood mulch. Heating materials to 130 degrees will kill both eggs and adult worms.

Practices to prevent jumping worms from coming onto your farm

It’s the season to think about planting, and a great time to think through some preventative practices to keep jumping worms off of your farm.

As you start your spring planting, here a few things to prevent the introduction of jumping worms:

• Make sure you buy compost, potting media and mulch from a reputable dealer that guarantees weed free material. We believe the same process that makes material weed free should make them jumping worm free. We are not sure if/how straw may be impacted by jumping worms.
• Clean your gear, footwear, tools and machinery to prevent the spread of weeds, invasive species and jumping worms from one site to another (think about prevention much like you would think about preventing pathogens on your farm - cocoons can move through the soil much like plant pathogens).
• If your home is at the same location as your farm, thoughtfully manage your home landscaping to prevent the introduction of jumping worms. In particular, be careful about trading perennial plants with others, as the cocoons and worms may be present in the soil or in plant roots. Once introduced to a property jumping worms can move surprisingly quickly across the property.
• Remember 130 degrees F is the temperature at which worms and worm eggs die.
  

If you think you have jumping worms report them using one of the following methods:

• Use the EDDMapS Great Lakes Early Detection Network (GLEDN) free mobile app.
• Report using the EDDMapS Midwest web-based mapping system for documenting invasive species.
• Report to the Minnesota Department of Natural Resources: Laura.Vanriper@state.mn.us or 651-259-5090.
  

For more information about jumping worms visit Extension’s jumping worm webpage.