Sep 10, 2016

Invasive Jumping Worms – Real Bad Guys

By: Lawanda Jungwirth

         I can’t tell you how much it creeps me out to write a column about worms. I’ve always been a little afraid of them and have avoided touching them at all costs. But I felt I had to write it. Didn’t want to, felt I owed it to you. So here goes. Eeewww!

         Most people know that earthworms in a garden are an indicator of healthy soil. In fact, worm castings (otherwise known as poop) are one of the best fertilizers in a garden. You can buy bags of the stuff and it isn’t disgusting or smelly. It looks like coffee grounds.

         Worms in forests are a different story and it doesn’t end happily. They consume the leaf litter that lays atop the soil too quickly, exposing the soil and contributing to soil compaction, erosion and runoff. Native plants die without the protective layer of leaf mulch and invasive plants are quick to take their place. Leaf litter layer also helps soil retain moisture, protects young plants, cools roots in summer, guards against damage from repeated freezing and thawing in winter and deters plant diseases. Without a layer of leaf litter the barren forest floor is left defenseless.

         So that’s been happening and it’s been a concern in Wisconsin forests for a while now. Now, there’s a new worm in town and it’s a bad guy, way worse than regular earthworms. This one has the potential to decimate home landscapes, parks, farm fields and forests. You read that right – this guy could appear in your own backyard.

         Jumping worms are native to Japan and the Korean peninsula and were first discovered in Wisconsin in 2013. No one knows how they got here for sure, but they probably arrived in mulch, soil, plants or the root balls of trees shipped to a nursery.

         There is no mistaking this worm when you see it. Or touch it anyway. Which I won’t be doing. They thrash and jump around vigorously when touched, like a disturbed snake, even jumping into the air. To make the nightmare worse, they sometimes shed their tails in defense. This explains the other names for them: Alabama jumpers, crazy worms, and snake worms. No offense intended to people from Alabama, crazy people, or snakes.

         Jumping worms are about the same size as any other earthworm, three to five inches, maybe as long as seven inches once in a while. But they look a bit different from other earthworms found in Wisconsin. The narrow band around the worm’s body, called the clitellum, is cloudy white and smooth and completely circles the body. On other worms, the clitellum is raised and doesn’t go all the way around. So you could remember that, or you could just touch it with a stick to see if it jumps.

         What you won’t see is just one jumping worm. There are always a bunch of them creepy-crawling around. You also won’t find them when digging underground. They stay on the soil surface to do their dastardly deeds.

         The big problem with jumping worms is they are extremely voracious in eating the detritus on the forest floor and then pooping it out to turn the soil into grainy, dry worm castings. Although some worm castings are good in the flower and vegetable garden, worm castings alone won’t support healthy plants. The forest understory plants die off, throwing the entire ecosystem out of whack. In residential areas, jumping worms harm ornamental plantings and turf.

         Jumping worms reproduce quickly. They don’t need a partner; they can reproduce on their own without mating. One worm inadvertently transported in a potted plant can begin a whole new population when it finds itself in a new location. Although the worms don’t survive our Wisconsin winters, they lay plenty of eggs in protective cocoons, too small to see with the naked eye, and those cocoons do survive the cold. Worms reach maturity within 60 days of hatching, so you’ll begin to see them in late June. Sixty days later, they in turn can lay new eggs. With the 60-day turn around, two generations are produced within a single growing season.

         I’ve referred to DNR Rule NR40 often in “Plant Matters,” always in reference to invasive plants. The rule also lists invasive animals, fish, diseases, fungi, even bacteria and algae. Jumping worms are listed in NR40 as RESTRICTED. This means that it is illegal to buy, sell, bring into the state, or release jumping worms to water or land in Wisconsin.


  • Arrive clean, leave clean. Clean soil and debris from vehicles, equipment, gardening tools and personal gear before moving to and from a work or recreational area.
  • Watch for jumping worms and signs of their presence. If you find them, report them to the DNR by email at
  • Educate yourself and others to recognize jumping worms.
  • Only use, sell, plant, purchase or trade landscape and gardening materials and plants that appear to be free of jumping worms.
  • Only sell, purchase or trade compost that was heated to appropriate temperatures and duration following protocols for reduction in pathogens. (See Wis. Admin. Code Ch. NR 502.12). 


All the earthworms native to the United States died in the last ice age. The ancestors of the 20 species of earthworms found in Wisconsin today were brought by European settlers. 

Photos courtesy of Bernadette Williams, Wisconsin Department of Natural Resources.