Pest Alert: Amynthas agrestis (crazy worm or jumping worm)

Tom Tiddens —  September 11, 2015 — 13 Comments

Unwanted wiggler discovered!

About a month ago, one of our horticulturists called me out to look at a groundcover planting that was being heavily disturbed by worms. At first look, I thought nothing of it—maybe it was increased surface worm activity from all the rain. A couple of weeks later, they were still very active, and the groundcover was actually floating on worm castings! We rolled it up to expose many worms. When I picked up a worm, it flipped out of my hand and wriggled away quickly, snake-like—not like a typical worm.

Since this activity seemed strange, I asked our senior ecologist to have a look at the crazy-acting worms. Coincidentally, he identified them as “crazy worms” (Amynthas agrestis), an invasive worm on his watch-for list that has never been found in Illinois. Samples were sent to the University of Illinois for confirmation, and the Illinois Department of Agriculture and Illinois Department of Natural Resources were informed. Our find has been confirmed—along with another find in DuPage County—and a potential find in Wilmette is being investigated. The crazy worm has been in the United States for many years in many of the southeastern states (and in the Smoky Mountains). In 2013, it was found in Wisconsin. DuPage and our find are the first confirmed for Illinois.

PHOTO: Crazy Worm (Amynthas agrestis).

Crazy worm (Amynthas agrestis)

Why is this worm bad?

  • They out-compete and push out our common European earthworms.
  • They multiply very quickly.
  • They devour soil organic matter and drastically change soil structure. This has a huge impact on forest ecosystems as well as on residential and urban ornamental plantings.

How do I identify the crazy worm?

  • They are found near the soil surface.
  • When touched, they respond immediately with a crazy flipping and jumping reaction.
  • They have a fast, snake-like movement.
  • Unlike a common European worm, they have a milky white flat band (clitellum).
  • They are 4 to 8 inches long.
  • A worm may lose its tail when handled.

What should I do if I think I have found the crazy worm?

  • Report the find to the Illinois Department of Natural Resources or Illinois Department of Agriculture.
  • To learn more about the crazy worm, just do a Google search on Amynthas agrestis (crazy worm or jumping worm).

Currently there are no treatments recommended for management of the crazy worm. Education and slowing the spread is the current course of action. The crazy worm’s primary means of spread is through the movement of plants with soil.


The Garden is a member of the Sentinel Plant Network, a group that unites botanic gardens in monitoring and providing education on exotic, invasive plant pests and pathogens, and works in partnership with the National Plant Diagnostic Network (NPDN).

If you are a plant and bug person like me, please consider becoming a NPDN First Detector and help be on the lookout for these exotic, invasive plant pests and pathogens. The NPDN offers an online training course to become a First Detector at firstdetector.org. It’s free, and upon completion, you even get a printable certificate!


©2015 Chicago Botanic Garden and my.chicagobotanic.org

Tom Tiddens

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Tom Tiddens is plant health care supervisor at the Chicago Botanic Garden. The Plant Health Care (PHC) Department monitors the Garden for insects and diseases on a weekly basis, as well as other plant health concerns, to discover, evaluate, and treat pest concerns in their early stages.

13 responses to Pest Alert: Amynthas agrestis (crazy worm or jumping worm)

  1. Tom. After reading your article, it got me thinking about the worms in my compost pile. When I turn the soil I unearth many worms. I thought that they were the standard european earth worm but now Im not so sure. When I unearth them they do flip around and seem much more active “crazy” than the normal worm. What now?

    Nick

    • Nick, if they match up to the description and characteristics I mentioned, you may want to report your possible find. Maybe first do a Google search on “worm identification,” and then if you still feel you have jumping worms, it is best to report it to the State (IDNR or IDA).

  2. Is there any difference very common night crawlers of my youth and the crazy worm described in your article. The worm described and pictured in your article is identical to night crawlers that we sought out for fishing bait. My earliest recollections go back over 60 years. They were available at bait stores and we dug for them in our gardens in Chicago, Evanston, and Glenview.

    • Great question Ralph!
      There are MANY types of worms and many have very similar looks. You are right—the common nightcrawler (Lumbricus terrestris) has similarities to the crazy worm, but one noticeable difference is the band (clitellum) is more pale and is not raised. Another important difference is that the nightcrawler is a deep-burrowing species (Anecic species) and the jumping worm is surface soil and litter species (Epigeic species). Nightcrawlers bring organic matter deep into the soil, and that benefits many soils; and the jumping worm devours surface organic matter, robbing the forest floor and truly not improving the soils. Sadly, the more aggressive crazy worm will push out the more beneficial common European worms, like the nightcrawler.

  3. I live in Barrington and we have those exact worms in my back yard, fish seem to like them fine. :))
    I just moved in and went fishing with the kids and pull up a log and the little guys sure to jump alot compared to the “regular worms” i had as a kid

    • Hi Rich,
      These could be jumping worms, but there are other worms that look very similar. If they match up to the description and characteristics I mentioned, you may want to report your possible find. Maybe first do a Google search on “worm identification,” and then if you still feel you have jumping worms, it is best to report it to the State (IDNR or IDA). Also, best not to move them far if you are using for fishing, as you don’t want to move them into areas where they are not already established.

  4. You can also download the MISIN app (Midwest Invasive Species Network) and report invasive species there, but do report to the DNR too. There is much to learn about these creatures as they reproduce by cloning and their cocoons can be spread by mulch, animals and even our shoes. Google: jumping worms, Wisconsin DNR. The corridor from Madison to Milwaukee is loaded with them.

    • The IL Dept of Agriculture came to our yard in DuPage Co. when I reported the jumping worms. The specimen were brought to U of I in Champaign/Urbana where they were positively identified as Amynthas agrestis, jumping worms. They were also found next door to us and across the street. (Two different sources of mulch.) I suspect we’ll be hearing more about this. If anyone hears of a workshop on this please let me know. The one I attended in northern Wisconsin this summer was very informative. The speaker was from the WI DNR in Madison. That’s how I learned to identify them and know to report them when I found them. I pulled a weed and there there were. It is a very serious issue in the northern forests so documenting their spread on MISIN is very important.

  5. Tom, it appears to me that you might have not only one but two Amynthas species there. The one pictured with the article might be a different species. The resolution of the picture is not high enough for proper identification, but some details of morphological characters look very suspicious. Co-occurrence of Amynthas agrestis with two other species is much more often than people have come to aware of.

  6. Martha Hellander April 25, 2016 at 1:08 am

    Tom, what specific ground cover was that where you found the worms last fall?
    Will the CBG be undertaking research on soil amendments or other strategies Chicago-area gardeners might use to discourage these worms? That would be most helpful!

  7. I laid bark mulch around my small back patio area this spring, and have these guys all over the place. I live in Indianapolis.

Trackbacks and Pingbacks:

  1. Jumping or Crazy Worms Confirmed on North Shore - August 25, 2016

    […] to the Chicago Botanic Garden’s Pest Alert: “Amynthas agrestis is a concern because they multiply very quickly, out-competing […]

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