A New Can of Worms!

Nebraskans are talking about an invasive worm. They are commonly referred to as “Asian jumping worms”, “jumping worms”, “crazy worms”, or “snake worms”. I like to call them crazy worms because whether they jump or move in a serpentine motion, they certainly behave in an uncharacteristic way for a worm.

The short story is that they are popping up in home landscapes everywhere, now that a Backyard Farmer question brought them to our attention. They are jumpy creatures when disturbed, trashing about wildly, and even dropping their tails to get away. They are bad for our environment because they feed on organic matter near or on the surface of the soil, releasing nutrients too quickly. Consequently, these nutrients wash away with heavy rains and change the soil structure in a non-beneficial way. What is left are loose, hard pellets that resemble spent coffee grounds. Without organic matter in the soil, plant roots have difficulty staying rooted. This is especially detrimental for forested areas and gardeners wishing to transplant seedlings in affected soils.


Crazy worms come in all sizes, but they are often found in large numbers near the soil surface feeding on mulch, fallen leaves, and other organic matter. (Photo: J. Green)

These crazy worms outcompete, outnumber, and out-consume other worms in our landscape and therefore have a significant impact on the ecosystem. If you find them in your landscape, please report your sighting to Nebraska Invasives and do your part to limit their spread.

End of short story.


Here is the long story if you want to know more…

Where are these worms located? 

Jumping worms were discovered in 2013 in Wisconsin. Today they are found in many places in North America including the northeastern and southeastern states, Texas, Oklahoma, Minnesota, Iowa, Nebraska, and Oregon.

What should we call these worms?

There are approximately 17 species of invasive jumping worms  and some species have co-invaded and exist together (Amynthas species and Metaphire species). It is difficult to identify worms to species without genetic testing or a dissecting microscope, so invasive worms have a number of common names which include Asian jumping worms, jumping worms, crazy worms, snake worms. When you see them, you will undoubtedly know that they are not your ordinary earthworms.

What do the worms look like?

Visually, the worms will vary based on the time of year. If you see a large worm in March or April, this will not be an invasive worm because invasive worms have an annual life cycle. Adults die each winter, but not before they produce (parthenogenetically/without mating) multiple cocoons in the fall. Cocoons are about the size, shape, and color of mustard seeds and cannot be easily detected in the soil. Cocoons survive the winter in the soil and hatch in the spring, developing rapidly to adulthood (60-75 days) by the end of the summer. Discovery of crazy worms is usually in August and September when worms are at their largest.

Crazy worms appear smooth and glossy and are rubbery to the touch, rather than slimy and squishy. A telltale sign is to examine the clitellum (light band) on mature worms. If the clitellum is a cloudy-white color, completely encircles, and is flush with the body, you are looking at an invasive crazy worm. If you happen to be digging through the top layers of soil and come across a pocket of crazy worms, they thrash and flick their bodies about, move side-to-side in a snake-like motion, and break off tail segments to escape. It can be quite horrifying.

Jumping worm in a human hand
Invasive crazy worm can be identified by clitellum, which is light in color, unsegmented, flush with body, and completely encircles the worm. (Photo: J. Green)

Without looking at the worm, a sure sign of crazy worms is the texture of the soil where they have inhabited. Rather than create a casting pile or middens like European earthworms and night crawlers, crazy worms will leave loose, granular soil particles that have the same consistency. Crazy worms are present in the topsoil, so if the mulch is being consumed at a faster rate than usual, crazy worms may be feeding underneath.

How are the worms spread?

The initial spread of crazy worms could be from a number of avenues, all of which involve the transport by human activities. Some worms may have originated as fishing bait, while others purchased worms for composting or vermiculture. The most common means of spread is by the movement of infested soil, mulch, or compost used for gardening and transferring plants into the landscape. Many people obtain plants and seedlings from community sales, friends, and neighbors in the fall. The soil that comes with the plants may contain tiny cocoons, which hatch the following spring.

How can I find out if I have crazy worms in my landscape?

If you are curious as to whether you have crazy worms, you can perform a mustard pour on a portion of your soil:

  1. Mix 1/3 cup of ground yellow mustard seed with 1 gallon of water.
  2. Clear a bare patch of soil and pour slowly over the soil.
  3. Worms will move to the surface and you can determine whether they are crazy worms or common worms.

What do I do if I find crazy worms?

  • If you find crazy worms in Nebraska, please report your sighting. The Nebraska Invasive Species Group is tracking the spread and updating the distribution map of crazy worms across the state.
  • Reduce the movement of soil to stop the spread of cocoons from one place to another. Clean equipment, garden tools, and personal gear like the treads of footwear between work sites. A good motto is “Arrive clean, leave clean.”
  • For some infested areas in open areas, solarization may be an option to kill the cocoons. This process involves laying a clear, plastic sheet over affected area in order to what the soil to a lethal temperatures, which often takes a couple weeks. Current research out of the University of Wisconsin-Madison Arboretum showed that 104°F/40°C killed cocoons after three days. 

Are there any control methods? 

There are no EPA registered chemicals labeled for the control of crazy worms once they are in the landscape. Some products, like Early Bird Fertilizer (Nitrogen-based) and tea seed pellets (Active Ingredient Saponin) have been tested, but additional research is needed to determine application rates and long-term effectiveness.

What can you do to prevent the spread of crazy worms? 

  • Educate others about crazy worms and how to identify them.
  • Buy plants from seed or bare-root (triple-rinsing roots will remove cocoons).
  • Do not buy fishing worms advertised as “snake worms”, “Alabama jumpers”, “crazy worms” or “jumping worms” for fishing or composting.
  • Do not dispose of unused worms in the environment.

Where can I go to find more resources?

For more information go to Nebraska Invasive Species Program.

I had the pleasure of speaking to lead researcher at the University of Wisconsin-Madison Arboretum ecologist, Brad Herrick, who is currently working on research aimed at controlling the spread of the cocoons. There is so little known about invasive worms in our various ecosystems. At this time, invasive worms have not been reported in agricultural land or food crops.

Jody Green, PhD
Extension Urban Entomologist at Nebraska Extension
Jody Green is the extension urban entomologist at Nebraska Extension in Douglas-Sarpy Counties. She specializes in structural, household, and health-related insect pests.
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