By Nancy Donovan, Ph.D., PT

Master Gardener Volunteer

Until I was doing the research for this column, I did not know that there were no native earthworms in Maine. In the Aug. 1, 2021, online issue of Maine Home Gardener News, an article that was first published in the April 1, 2019, issue of the same online newsletter, Gary Fish wrote that, “Due to our history of glaciation, there are no native earthworms in Maine. Non-native earthworms from Europe, such as night crawlers, became well established in Maine through early colonial trading with Europe. While beneficial to gardens, earthworms are known to have destructive effects on our forests.” The article in which this information was published is titled, Crazy Worms in Maine.

(https://extension.umaine.edu/gardening/2021/08/01/maine-home-garden-news-august-2-21/#article-2/)

While I recall going out at night with a flashlight to pull earthworms from the soil so that my mother and stepfather could go fishing (I stopped joining them after my stepfather’s casting method resulted in a worm in my hair), the Crazy Worms in Maine article was written about a worm that no one wants to find in a home garden, or anywhere in Maine. The crazy worms have also been called Asian jumping worms, snake worms, and wriggling worms. The scientific name is Amynthas agrestis. While the earthworms I was looking for way back then continue to be welcome sights in home landscapes, the presence of the jumping worms is a cause for distress. In an article titled, Jumping/Snake (Amynthas) Worms in Maine that can be found on the website for the Maine Department of Agriculture, Conservation & Forestry (DACF), the authors wrote that, “Amynthas worms are a type of earthworm native to East Asia. They are smaller than nightcrawlers, reproduce rapidly, are much more active, and have a more voracious appetite. This rapid lifecycle and ability to reproduce asexually gives them a competitive edge over native organisms, and even over nightcrawlers. When disturbed, Amynthas worms jump and thrash about, behaving like a threatened snake.”

The species of earthworms we typically see in our gardens are welcome due to the fact that they aerate the soil which allows oxygen, water, and nutrients to reach the roots. They also enrich it with their excrement, called castings or poo. While earthworms are not required in garden soil, they are present in moist, loamy soil. Indeed, many gardeners purchase worm castings to add to their garden soil. The “Gardening Know How” website outlines in an article titled, Using Organic Worm Castings: How to Harvest Worm Castings for Your Garden written by Nikki Tilley, that, “Worm castings are an organic form of fertilizer produced from earthworms. Also known as vermicast, worm castings manure is essentially earthworm waste, otherwise known as worm poo. As these creatures eat through compost, their waste creates an optimal soil enricher. Worm castings resemble football-shaped particles that improve soil aeration and drainage, as well as increase water retention in the soil.”

The DACF article cited above reported that the jumping worm is native to Korea and Japan and was first documented in a Maine greenhouse in 1899. Research now indicates that there is an established population in Maine. The website contains a map of the locations where the jumping worm has been definitively found. Unfortunately, the map shows that the jumping worm was found in Bridgton in 2021.

(https://www.maine.gov/dacf/php/horticulture/jumpingworms.shtml

While differentiating the various species of earthworms can be difficult, there are identifying characteristics that you can look for to determine if you have the jumping worms in your soil. One of the first things you can do is to take a close look at the top layer of your soil. The University of New Hampshire Cooperative Extension wrote about the jumping worm in an article titled, Invasive in the Spotlight: Jumping Worms published on their website on March 26, 2018. The authors reported that since the jumping worms live and feed close to the surface of the soil, and they are known to be voracious eaters, the castings they leave behind resemble coarse coffee grounds. Gardeners can also scratch through the top layer of soil to see if the worms are present and thrash about when you touch them.

Another identifier is that while other earthworms have a band that is raised from the body of the earthworm (called a clitellum), it is reddish and close to the color of the body of the worm and does not wrap entirely around the body. The clitellum of the jumping worm is whitish or gray in color, is not raised off from the body (it is smooth), and it wraps entirely around the body. Of course, a telltale identifier is the thrashing or writhing, fast-moving motion that you will see if you touch the jumping worm. There is a good video that you can watch on the DACF website. (Warning… while I have never eaten gummy worms, you may never eat them again if you watch the video.)

The best time of the year to search for the worms is from late June through mid-October. The reason is that the adult jumping worms die after the first freeze of the year, but the cocoons, which are approximately the size of a mustard seed, survive and hatch when temperatures are consistently above 50 degrees. There is also a relatively easy way to see if jumping worms are present in the soil. It is called the mustard test. The directions are to mix ? cup of ground mustard into one gallon of water and pour the solution slowly over a one square foot of soil you want to test. This will make worms (any earthworms) come to the surface. You can then identify, collect, and discard jumping worms in sealed plastic bags and place in trash. According to a factsheet published by Cornell University titled, Invasive Species for Homeowners: Jumping Worms, the mustard test “ …is unlikely to harm most plants…” What is known is that allowing the jumping worms to remain in an area can be very detrimental to plants and animals. (The link to the Cornell factsheet is available in the DACF article.)

The article cited earlier from the University of New Hampshire Extension website provides several actions that you can take to try to prevent jumping worms from invading your landscape/gardens.

“Do not buy or sell mulch, topsoil, compost, or plants that are infested with jumping worms. Before bringing these products home and introducing them to your landscape or garden, carefully inspect the materials for signs of jumping worms and their castings. Be especially careful when sharing plant material at community plant sales and swaps. Jumping worms will readily crawl in to reproduce within nursery pots. If you know you have jumping worms in your garden, it’s better to avoid sharing plants with other gardeners.

Before you purchase any new plants, take a close look at the potting soil. If jumping worms are present, you will see signs of their telltale, coffee-ground like castings on the soil surface. To make sure you aren’t introducing jumping worms with new plantings, try to remove most of the soil from the root ball of a new plant. Knock off the soil into a garbage bin and rinse the roots with water to remove any remaining soil.

Jumping worms are occasionally sold as fishing bait or for use in vermicomposting. Do not purchase them for these purposes or any other purpose and do not release them into the garden.”

The article from Maine also requests that you provide information regarding where you found the jumping worms. The website asks that you “Please visit the DACF iMap Invasives web page for more information.”

I have not continued my mother and stepfather’s fishing expeditions, though I still have vivid memories of her peculiar casting method, which was different from my stepfather’s. She held the fishing rod with both hands over her head and threw the rod forward similar to an overhead pass in basketball. I have never again seen that method. I will never forget her giggling as she told the story of how she caught a fisherman’s hat as he passed by in his boat. I suspect that the bait was not a jumping worm, and I further suspect that the fisherman altered the path of his boat if he saw my mother fishing from the shore in the future. While jumping worms are no laughing matter, the memories of watching my mother fish make me smile.