Amynthas agrestis

Amynthas agrestis, more commonly known as the Asian jumping worm or crazy worm, is a species of invasive earthworm. They are relatively new in the United States and can be found in the Southeast, along the Eastern Seaboard, in the mid-Atlantic, Midwest, and some Northwestern states. They outcompete native earthworm species by taking over a section of the forest floor until the resources have been exhausted before moving on to another section of forest. They have a devastating effect on forest floor substrate and the vital nutrients that make up the food web of the forest as a whole. (Add in text citations - Leanne)

Asian Jumping Worm in comparison to an individuals fingers

Scientific Classification

Kingdom- Animalia

Phylum - Annelida

Class - Clitellata

Order - Haploxida

Family - Megascolecidae

Background

In the Northeast during the last ice age around 10,000 years ago, massive glaciers scraped the bedrock bare as they receded over hundreds of years. This removed any native earthworms that were originally present in this area. Since then, humans have brought new earthworms over from Europe and there is an ongoing debate whether these species are helpful or harmful. It is generally assumed that they are doing more good than bad. The Amynthas agrestis is from Japan and Korea and are very aggressive and notably different from the European earthworms.

Crazy worms can spread to new areas by hitchhiking long distances in potted plants or mulch. There are two ways of telling if your potted plant is harboring invasive earthworms. One way is to turn the plant upside-down and gently remove the root ball. If crazy worms are present, the roots, as well as some potting soil, may be missing. However, if only young crazy worms are present or there are very few, damage may not be evident. The second and better way of telling if they are present is a mustard solution. Mix one gallon of water with 1/3 cup of ground yellow mustard seed, and pour the mixture slowly into the soil. Any worms in the soil (even “good” ones) will come to the surface and they can be checked for any invasive species.

Video Depicting Amynthas Agrestis: "https://www.youtube.com/embed/Ca7n3Gf3xX4"

Characteristics of Amynthas Agrestis

Amynthas agrestis can be distinguished from other worms by their darker color and by the band near their middle called a clitellum. In most worms it is puffy and similar in color to the rest of the body. In crazy worms it is even with the body and milky white to gray. They are typically iridescent, and violet colors in direct sunlight. Mature size and behavior also set them apart. Crazy worms are very hyperactive and slither like a snake, which is not normal of other annelids. They will shed their tails to escape predation similarly to their close relative the Alabama Jumper (Amynthas gracilis). Their vermicast is very large and has the appearance of cooked ground beef.

Because of their acrobatics crazy worms are valued as fishing bait, and despite it being illegal in most areas they are still commonly used as bait. To be safe, anglers should securely cover bait containers and destroy all unused bait by placing it on bare concrete and stepping on it. With a presence in Wisconsin and Minnesota, Amynthas agrestis is hardy to USDA Zone 4 and possibly colder.

Reproduction

Most earthworms are hermaphroditic which means that they have both male and female reproductive organs. However, they still need a mate to complete the reproductive process. Amynthas agrestis on the other hand are parthenogenic, meaning they are all females. They reproduce by making cocoons filled with hundreds of babies that are also female, which means it only takes one crazy worm in any given area to lead to infestation.

Amynthas agrestis also mature at twice the rate of European earthworms, finishing two generations per season instead of one. Their population density is also greater than other earthworms, and they are a much larger species and grow to around 8 inches long. All of these features lead to a massive Amynthas agrestis biomass in areas where they are established. "In areas of heavy infestation, native plants, soil invertebrates, salamanders, birds and other animals may decline. By disturbing the soil, jumping worms help facilitate the spread of invasive species. Jumping worms can severely damage roots of plants in nurseries, gardens, forests and turf." This includes lawns as well as the roots of annuals, perennials, and shrubs. In the forests, they destroy the native wildflowers, wiping out such plants as trillium, bloodroot, Jack-in-the-pulpit, lady slipper, and other understory plants. As these understory plants disappear they take with them the understory songbirds with them. As Amynthas agrestis infestation removes organics from soil, the soil becomes clumpy and granular and prone to compaction and erosion. Forest soils actually subside, exposing tree roots. Wisconsin Department of Natural Resources invasive species specialist Bernie Williams stated “Their introduction into our state poses a huge threat to the future of our forests.”