"Soil is the foundation of life – and Asian jumping worms change it. Earthworms can have such huge impacts that they can re-engineer the ecosystems around them," Mac Callaham, soil specialist at the US Department of Agriculture.
In thirty-four states, the 'Asian jumping earthworm' (Amynthas agrestis) has been found where they never were before. The species is native to Japan and Korea and is about eight inches long with a white stripe. When threatened, the worm can jump up to a foot in height and thrashes around like a snake when disturbed.
Scientists are very concerned by the discovery as the worm devours the top layer of soils in forest ecosystems. Recently discovered in the heavily forested state of California, researchers worry about the impact on forest soils. Soil microbes and insects, birds, and mammals enrich the ground and keep forests healthy.
Why do we care about forest soils, you may ask. We desperately need carbon sinks in an era of climate change, and they absorb almost one-third of CO2 emissions. Forests provide naturally freshwater to organisms in the woods and in some major cities across the planet.
“These earthworms are extremely active, aggressive, and have voracious appetites,” the California Department of Food and Agriculture (CDFA) said in a report. “True to their name, they jump (known to jump off the ground or out of a bait can) and thrash immediately when handled behaving more like a threatened snake than a worm, sometimes even breaking and shedding their tail when caught.”
A specimen was spotted at a nursery in Napa County in July of 2021. While no further specimens have been reported in California, the CDFA said it was likely that the species would spread widely throughout the state.
Native to Japan and the Korean Peninsula, the earthworms are considered an invasive species in the U.S. because they did not evolve alongside other species in the country and can, in fact, have a negative impact on them, the U.S. Department of Agriculture’s Forest Service explained. This is because the species – also known as Alabama jumpers, Jersey wrigglers, wood eel, crazy worms, snake worms and crazy snake worms – devours the fallen leaves that cover the forest floor and create the top layer of its soil. While this is standard fare for earthworms, what is not standard is the speed at which the jumping worms devour their leafy food. They can consume a forest’s entire leaf layer in two to five years, according to CDFA.
They replace the leaf-layer soil with a soil composed of worm castings that does not provide a home for understory plants and is dominated by bacteria rather than fungi, according to CDFA. This accelerates the conversion of leaf debris to minerals and means that plants do not have as many organic nutrients to consume. Because the forests now have fewer plants and poorer soil, they are more at risk from erosion and disease. This is especially a problem for hardwood forests that contain maple, basswood, red oak, poplar or birch.
“Some northern hardwood forests that once had a lush understory are reported to now have only a single species of native herb and virtually no tree seedlings,” CDFA said.
The worms were first brought to the United States around 1900. Most likely in the soil of potted plants. They have only started to spread into forests and spread rapidly across the North American continent.
Critical points on the worm from the University of Maryland:
Worms referred to as jumping worms, crazy worms, snake worms, Jersey wigglers, Georgia jumpers, and Alabama jumpers include three similar-looking species: Amynthas tokioensis, Amynthas agrestis, and Metaphire hilgendorfi, all of which are in the family Megascolecidae. Two or three species often occur in the same location.
They are all non-native species, originating from Asia.
They have an annual life cycle; the adults die after the first hard frost; the next generation survives the winter in the form of cocoons (egg casings). They hatch and survive when the soil temperature is consistently about 50˚F. They develop into full-size adults in about 60 days. Climate change may be increasing the number of generations to two per year. They have “boom” and “bust” cycles from year to year.
Individual worms can reproduce without a mate (parthenogenesis) and their populations can increase quickly. They displace and out-compete other earthworms.
They live only at the surface level of the soil and leaf litter (epi-endogeic) and therefore do not help gardeners with deep soil aeration, nutrient movement, or water infiltration.
They can digest wood and favor areas with leaf mulch; areas with pine needles and native grasses are less attractive to them (source: University of Wisconsin-Madison).
In recent years, the worms have made news in the eastern states; This is the first time I had heard of them before, as they are now spreading like wildfire and have brought more scrutiny from the press.
Invasive jumping worms consume large amounts of organic matter and change surface soil composition. They make the soil more gravelly in structure, drier, more prone to erosion, and less favorable to normal soil microorganisms (fungi, bacteria), and plant growth. The worm castings (feces) sit on top of the soil, leaving nutrients out of reach of plant roots and increasing the risk of nutrient runoff.
Any organism that relies on the normal composition of a natural forest floor for food and/or habitat will be disrupted by invasive jumping worms. This includes native plants, insects, birds, and other animals. A forest floor depleted of its normal mulch layer is less hospitable for seed germination and native plant establishment.
In a home garden, soil disruption from jumping worms can diminish the growth of annuals, perennials, and turfgrass.
What's wild is how quickly the torn segments can tunnel into the soil. It is recommended that if stumbled upon that, the worm be killed. Yeah, that was suggested for the Boa in the everglades. It didn't work.
For gardeners that have an infestation. Dry mustard?