Background/History
Earthworms are not insects. They are typically classified within the Phylum Annelida (segmented or ringed worms) and Class Clitellata (worms possessing a type of collar structure which holds importance during reproduction and can be used in identification). Glacial activity in the Pleistocene is thought to have eliminated what would have been most of the native earthworm species from Canada and the northern United States at the time. Few native earthworms remained in the areas impacted by the glaciers by the time of European settlement. Since then, at least 45 non-native species of earthworms have been introduced into North America (north of Mexico) from areas such as Europe, Africa, Asia, and South America (Hendrix and Bohlen, 2002).
According to past literature, at least 21 species of earthworms have been collected from various locations in Massachusetts, including Amynthas agrestis, one of the various species receiving a lot of attention recently and commonly being referred to as “jumping worms, crazy worms, crazy snake worms, or Asian jumping worms”, among other names. Amynthas agrestis, for example, was previously reported in Hampshire County on October 9, 1974 and Suffolk County in Boston, MA as reported by Gates (1953) and at the time referred to as Pheretima agrestis (Reynolds, 1977).
Recent Extension publications and outreach from other states has called to light concerns that these particular species cause further damage to forests and perhaps even landscapes through their ability to alter the soil structure and chemistry of these locations. They are able to consume a critical layer of organic matter that supplies nutrients vital for other wildlife, particularly in forests. The current concern seems to be that certain species of Asian origin may devour organic matter more rapidly than their European counterparts. Some state Departments of Environmental Conservation (such as New York) are going so far as to prohibit the possession, sale, import, purchase, or transportation of these species.
As such, residents of Massachusetts have become increasingly concerned and recently are reaching out to UMass Extension for help. The intent of this article is to share more information about the history of earthworms in Massachusetts, along with information about the “crazy worm” species of concern, in hopes that this material can aid citizens who are presently apprehensive of these species.
Species Known Previously to Massachusetts and their Origins
The following table of earthworm species previously detected in Massachusetts, along with their origins, is adapted from Reynolds (1977) and Hendrix and Bohlen (2002).
| Earthworm Species Detected in MA |
Area of Origin |
|---|
| Amynthas agrestis |
Asia |
| Amynthas hawayana |
Asia |
| Allolobophora chlorotica |
Europe |
| Allolobophora limicola |
Europe |
| Aporrectodea longa |
Europe |
| Aporrectodea trapezoides |
Europe |
| Aporrectodea tuberculata |
Europe |
| Aporrectodea turgida |
Europe |
| Bimastos parvus |
North America |
| Dendrobaena octaedra |
Europe |
| Dendrodrilus rubidus |
Europe |
| Eisenia fetida (Previously known as E. foetida) |
Europe |
| Eisenia rosea |
Western Palearctic and Nearctic |
| Eiseniella tetraedra |
Europe |
| Eisenoides lonnbergi |
North America |
| Lumbricus castaneus |
Europe |
| Lumbricus rubellus |
Europe |
| Lumbricus terrestris |
Europe |
| Octolasion cyaneum |
Europe |
| Octolasion tyrtaeum |
Europe |
| Sparganophilus eiseni |
Nearctic |
Why is There Concern?
It should be first mentioned that the “Asian crazy worm” or the “Crazy snake worm” or “Asian jumping worms” are not directly harmful to people or their pets. Although they may quickly writhe or squirm when disturbed and may move like snakes, they pose no direct physical threat to people.
Certain aspects of earthworm activity and the ecological impacts they can have are considered undesirable in certain locations, such as forests. Such impacts include, but are not limited to: removing and burying soil surface “residues” which otherwise can protect soils from erosion, increased erosion due to the productions of casts, increased compaction of surface soils, nuisance deposition of casts on lawns and golf courses, dispersion of weed seeds in certain environments, transmission of plant and animal pathogens, increasing the loss of soil nitrogen (leaching and denitrification), and increasing the loss of soil carbon through enhanced microbial respiration (Hendrix and Bohlen, 2002).
Recent reports regarding the species referred to as “jumping worms, crazy worms, crazy snake worms, or Asian jumping worms” cite a marked reduction in the amount of leaf litter on the forest floor or rapidly disappearing garden mulches as issues directly noticed by concerned citizens where these worms are present. Even wood chips are being reported as rapidly consumed where these species are present.
Past Recognized Benefits of Earthworms
In agricultural and pastoral systems, earthworms have often been shown to have beneficial impacts to soils. In these specific locations, the fact that earthworms can increase the rate of plant litter decomposition and increase nutrient transformation and plant nutrient uptake are seen as valuable impacts of these organisms. Other positive influences earthworms have in these locations include improvement of soil aggregation and porosity, along with enhanced water infiltration and solute transport (Hendrix and Bohlen, 2002). Essentially, earthworms can be beneficial in agriculture due to positive impacts on soils in those settings, increased nutrient and water availability, and the stimulation of certain microorganisms that in turn stimulate plant growth.
That said, these interactions are not considered beneficial in all locations. For example, as previously mentioned, some of these interactions are considered detrimental in forest settings.
What Can Concerned Citizens Do?
There is no permanent “cure” or method through which these Asian or European earthworm species can be eradicated due to their long history in North America and Massachusetts (since European settlement for some) as well as aspects of their biology. With regard to the “crazy worms”, these species are not known to overwinter as adults, but rather perish with the onset of cold temperatures, but their young are able to survive in tiny, resilient cocoons which are very small in size and the color of the soil surrounding them. Therefore, these cocoons can be nearly impossible to spot with your own eyes and are easily moved (albeit accidentally) in these substrates.
It seems that at this time, if a citizen is concerned about these earthworms, they can aid in reducing their spread by avoiding actions that increase their rate of distribution through human mediated movement. Reportedly, “crazy worm” species naturally expand their range very slowly. For example, a best management practice may be to avoid purchasing these species for fishing bait or vermicomposting, or avoid moving soils or compost where these worms are present to new locations.
If you think you have “crazy worms” in your garden, do not panic. While you may not be able to eliminate them from your garden, you can still play a part in preventing their spread.
Further Resources:
Cornell University Cooperative Extension:
http://ccetompkins.org/resources/jumping-worm-fact-sheet
Plant and Soil Science, University of Vermont:
http://blog.uvm.edu/jgorres/amynthas/
University of New Hampshire Cooperative Extension:
https://extension.unh.edu/blog/invasive-spotlight-jumping-worms
Works Cited:
Hendrix, P. and P. J. Bohlen. 2002. Exotic Earthworm Invasions in North America: Ecological and Policy Implications. BioScience. Vol. 52 No. 9: 801-811.
Reynolds JW, Görres JH, & Knowles ME 2015. A checklist by counties of earthworms (Oligochaeta: Acanthodrilidae, Lumbricidae and Megascolecidae) in the states of Maine, New Hampshire and Vermont, USA. Megadrilogica 17: 125–140.
Reynolds, J.W. (1977) The Earthworms of Massachusets (Oligochaeta: Lumbricidae, Megascolecidae and Sparganophilidae). Megadrilogica, 3, 49–54.
Tawny Simisky, Extension Entomologist, UMass Extension Landscape, Nursery, & Urban Forestry Program
