Jumping “Crazy Snake” Worms in The Last Green Valley

Jumping “Crazy Snake” Worms in The Last Green Valley

My friend Dick Waterman from Hanover, one of the three villages of Sprague, is a regular reader of this column. Thanks to his inquisitive nature, coupled with years of documenting the natural world in his neighborhood, he has provided me with several ideas to share with readers. He recently sent me information about snake worms and inspired today’s column.

“It should not have taken me as long as it did to realize that there was something weird about the behavior of the local night-crawlers I had been observing for the last couple of years. After all, I was introduced to fishing at a very early age, and knew that worms were the best bait, and big, fat night-crawlers were the biggest and best.”

“Night-crawlers, as their name states, are not typically seen above ground during the day, venturing out at night in moist grass. Sometimes one gets in over its head and drowns in a puddle; worms need to come up for air, which is why when it rains, they clear their tunnel by emerging from the ground during rains. But in recent years I have seen night-crawlers along the sides of roads, and sometimes in the road, and I have rescued more than a few, though these worms had a tendency to wiggle a good deal while trying to escape; it is a behavior that is not characteristic of the night-crawlers I would catch at night; the nocturnal variety immediately surrender themselves to capture.”

“It was last year in mid-summer. I was in my hay field that had recently been mowed, and I was raking thatch along a shaded slope, using a steel-spring lawn rake. As I aggressively scratched the ground, I noticed what appeared to be a night-crawler moving along the ground, rather swiftly I thought. Then I saw another, and another. Continued raking produced more fish bait that I could use in a week. It was fascinating to see this, and never had I noticed it before.”

“This year, again in July, my neighbor’s grandkids wanted to learn how to fish, and I offered to take them to a local pond. Remembering the success I had last summer, I went to the same site, and sure enough, as soon as I started raking, I had shiny, slimy night-crawlers slithering through the grass, trying to get away. Though easy to grab, I noticed that if I did not take care to grasp the worm fully, but rather by the rear portion, the “tail” would fall off, a defense mechanism familiar to amateur herpetologists. That finally did it. I knew this was definitely not my grandfather’s night-crawler. Surely this was a completely different worm.”

Dick looked to the internet to find the answer and found several entries discussing an invasive species of worm originating in Japan and Korea referred to as the crazy snake worm, snake worm or Asian snake worm. The scientific name is Amynthas agrestis, and there are other similar species. Dick’s research found this worm to be detrimental to native plants and reforestation. He is however happy to report they make excellent bait for fishing.

Thanks to Dick’s tip, I did a bit of research on my own and discovered more startling information about yet another invasive species impacting our environment. For several years we have felt the detrimental impacts of invasive plants such as Japanese barberry, Asian bittersweet and winged euonymus (burning bush), and invasive insects such as emerald ash borer and Asian long-horned beetle. But an invasive worm seems to be something out of a bad horror flick.

From the University of Vermont, I found this description:

“The Crazy Snake Worm (Amynthas agrestis), is an aggressively invasive earthworm that hails from Korea and Japan. These worms are in the family of Lumbricidae. The new invaders are from East Asia and are in the earthworm family Megascolecidae. There are several Amynthas species in the Northeast. These species are usually called Jumper worms (Alabama Jumpers), Wrigglers (Jersey Wrigglers) or Snake Worms… These worms are very aggressive invaders that change forest structure and the decomposer community in the affected forests.”

The complete article by Josef Gorres of UVM Plant and Soil Science can be found at:


Here is Connecticut we have one of the leading experts on these invasive worms, Dr. Annise Dobson, a postdoctoral researcher in the Yale School of Forestry & Environmental Studies. I found a lengthy article in Atlantic Magazine about her work along with interviews of other experts. It can be found at:


Last year Dobson published an article in “Connecticut Gardner” and here are some key points:

  • Jumping worm distribution is patchy throughout North America and the state, but Dick’s experience is becoming more frequent. Once introduced to a location, jumping worm populations grow rapidly, and can grow to high densities in 4-5 years. They grow and mature more quickly than native and European earthworms, and some species can reproduce asexually.
  • While both European and jumping earthworms eat the same things, jumping worms change the soil in a way that local flora is not adapted to. Jumping worms create large macroaggregates Dobson described as “gravelly, with the appearance of ground beef or spent coffee grounds.” These changes lead to soil erosion, nutrient leaching, root desiccation and plant death.
  • Jumping worms can be confirmed by observing behavior and key features of the earthworms including the previously mentioned thrashing behavior and high densities. Jumping worms are smooth, have a metallic sheen, are often darkly pigmented, and can be 1.5 to 8 inches long.
  • So far there are no viable control strategies to share so the emphasis is on limiting the spread of these worms through our own actions. The spread of jumping worms is mainly through dumping yard waste into natural areas and transporting mulch and soil with jumping worm eggs (sometimes called cocoons) or adults. Best practices should include requiring clean equipment provisions in logging and landscaping contracts, heat-treat compost and mulch (130°F for three days is best but 104°F for three days should be sufficient), prevent dumping of yard waste, plant bare-root and check for cocoons that are approximately the size of a slow-release fertilizer pellet. Dobson also recommends not to move soil in tools, equipment and shoes and not to use compost and mulch of unknown origin. Both cocoons and adults will disperse with gravity downslope and through waterways.
  • If you think you have seen a jumping worm in Connecticut, please upload your findings onto the iMapInvasives website – org. Researchers are actively using this information to understand jumping worm movement, which will inform best practices to prevent their further spread.

The complete article can be found at:


Thanks to Dick Waterman I have a whole new appreciation for worms and will be on the lookout for crazy jumping snake worms.

We live in a beautiful place called The Last Green Valley. Our natural world faces many challenges from invasive species – including snake worms. The more we understand these unique animals the better armed we are to prevent their spread and destructive force.

Bill Reid is the Chief Ranger of The Last Green Valley National Heritage Corridor. He can be reached at bill@tlgv.org


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