As gardeners eagerly anticipate another gardening season, it’s important to be on the lookout for jumping worms. While the name sounds like something from a bad science fiction movie, jumping worms (Amynthas species) originate from eastern Asia and reportedly have been in the United States since the 19th century. However, it’s only somewhat recently that we have begun to hear about them in Minnesota because of the visible destruction they are bringing to forested areas and gardens.
Jumping worms are a type of earthworm, but they differ from the European earthworms we typically see in our gardens in several ways. First, they tend to be darker in color. Because they live and feed in the top two to four inches of soil, their darker pigmentation protects them from ultraviolet rays. Also, the clitellum, the ring indicating sexual maturity that we see around an earthworm, is closer to the head of the jumping worm, lighter in color, and circles the entire body. It also is flatter in appearance, unlike the clitellum of the European earthworm that appears to be swollen and does not circle the body. In addition, when disturbed, jumping worms wriggle more actively than the European earthworms because they have many more tiny hairs called setae around each segment of their bodies. This allows them to be in contact with more of the ground’s surface and move vigorously, hence the name “jumping worm.”
The burrowing of jumping worms threatens plant growth, but they are also a significant threat because of the way they change the structure of our soils. Unlike European earthworms that leave nutrient-rich castings (poop), jumping worms strip the soil of nutrients, and their castings sit on the surface of the soil and wash away or erode. If you see what looks like cat litter or coffee grounds on the top of your soil, you may have jumping worms. If you’re hiking in the woods, you may notice exposed tree roots which may also indicate the presence of jumping worms. Because they feed on leaf litter, decomposition in these areas is occurring more quickly. European earthworms also contribute to this process, but jumping worms are accelerating erosion and have a negative impact on the whole ecosystem.
Jumping worms have been confirmed in Minnesota since 2006, mostly in the Twin Cities metropolitan area and in Rochester. Adult jumping worms live for only one season and cannot survive our winters, but their egg cocoons do. It is not practical to attempt to remove the egg cocoons because they are very small and resemble soil particles. To learn where sightings have been confirmed in Ramsey County, go to Cases of Jumping worm in Ramsey County, MN to see if jumping worms have been reported near your location.
While efforts to find research-based control methods are being accelerated, there are several things home gardeners can do now to prevent or slow the spread of jumping worms:
Look carefully for jumping worms in your soil, potted plants, mulch, and compost.
Don’t move any of the above materials to other locations if you suspect you have jumping worms. Moving mulch from one location to another is a key method of transport.
If you take garden tools to another location, wash them thoroughly first.
Don’t leave bags of mulch outdoors. Even commercial mulch is easily contaminated, especially when piled up in the open air. As for deliveries of mulch by the yard, researchers have observed jumping worms slithering towards recently deposited piles of mulch. They love wood chips!
If you purchase worms for composting, check your order carefully for jumping worms.
Be very careful about sharing plants with neighbors and friends. Washing plant roots in water may help prevent the spread of jumping worms, but it’s not a guarantee that you have eliminated them because the egg cocoons are so small.
If you find them in your garden, put them in the garbage. Do not release them.
In a recent presentation for the Garden Club of Ramsey County on March 15th, Dr. Lee Frelich, Director of the University of Minnesota (U of M) Center for Forest Ecology, shared that jumping worms do not like acidic environments, so gardeners may wish to use mulches that are higher in acidity such as pine needles or cocoa mulch. However, he also emphasized that jumping worms don’t need mulch to thrive; cool and wet soil is their preference. To learn more about jumping worms, go to Invasive Jumping Worms: Impacts and Prevention to watch a short video where Dr. Frelich explains how to identify the jumping worm and its impact on the environment.
Finally, if you suspect you have jumping worms in your garden, please take a clear picture of one of the worms against a light-colored background and report your findings to Laura Van Riper (laura.vanriper@state.mn.us) at the Department of Natural Resources. You can also become a citizen scientist. Visit Jumping worms: Report management and register to help researchers at the U of M with their efforts to find methods for managing this invasive pest. Research is in the early stages, and scientists welcome input from home gardeners who can help them understand what gardeners are doing and if it appears to be working. Your efforts may just lead to a science-based effective control method for jumping worms!
Additional Information
Image
Title: "Invasive earthworm Amynthas agrestis" licensed under CC BY-NC-SA 2.0
Photographer: Tom Potterfield