When I dig in my garden soil in spring, I look forward to seeing earthworms, since I know they add to the humus in the soil with their castings.
But with the invasion of the Snake worms that’s changing - as they destroy flower beds, lawns, and even some forests in the northeastern United States.
The crazy snake worm, native to Japan and Korea, came here in the 1980s on plant material. Since the worm’s arrival in New York State, it’s been spreading along the East Coast, including Vermont. It’s now banned in New York but it’s already been found in all counties of Connecticut. It grows to about eight inches long, gets its name from its writhing, snake-like behavior, and can be identified by a light-colored band that encircles its body.
Glaciation wiped out our own native earthworms 10,000 years ago, and our forest ecosystems evolved without them. The 16 to 20 species now seen in the northeast were introduced by European settlers, and the ones with which we are most familiar are nightcrawlers and red worms. It’s believed they came here either in the soil of plants that immigrants brought with them, or in the ballast of ships.
Earthworms are perceived as being beneficial because they aerate, or “aggregate,” the soil, but the crazy snake worm takes aggregation to a new level, breaking down the soil to the point that it can no longer hold water, so the soil dries out very quickly.
Josef Gorres, a soil scientist at the University of Vermont says these worms are incredibly voracious, feeding very quickly on the spongy layer, known as the duff, on top of the mineral soil. This spongy layer is the seed bank and the germination medium for most of the under-story plants. So once the worms have destroyed that duff layer, the understory plants disappear.
The loss of the understory in turn causes other ecosystem changes. Amphibians like salamanders lose food and habitat, as do many ground-feeding and ground-nesting birds. Deer that can no longer find food such as acorns on the forest floor eat saplings instead, preventing the forest from regenerating.
These changes are worrisome, especially in Vermont, where maple syrup production is an important industry. Nobody knows how many forests have already been altered by the worms, and the potential economic impact has yet to be calculated.