Earthworms are good, right? This is what most of us assume. But before we dive back into springtime mulching and planting season, have you heard of jumping worms?
They are known by several different nicknames, i.e., crazy worms, snake worms, Jersey wigglers, and Alabama Jumpers, due to the thrashing behavior they exhibit while trying to escape. Whatever you choose to call them, Amynthas agrestis, Amynthas tokioensis, and Metophire hilgendorfi, all native to Asia, are listed as “species of concern” in several states including NY. Unfortunately, they are spreading in our area, most likely through the transfer of mulch, compost, leaf litter and plants. Often sold as fishing bait in the past, they are now prohibited by the NYS DEC. This means you cannot “knowingly possess with the intent to sell, import, purchase, transport, or introduce” jumping worms.
Earthworms were mostly eradicated in the northern United States during the last glacial advance. The forest ecosystems that exist in this region evolved without worms as decomposers, relying instead on fungi, microflora, and fauna to slowly release nutrients. However, through human activity and movement, European earthworms were introduced as early as the 1600’s and are what we are most familiar with in our gardens and lawns. Jumping worms arrived in the US about a century ago from Asia, but in the past 15 years have begun to spread widely and have only recently become a concern in NYS.
Why are they so concerning? Unlike European worms, jumping worms tend to live in the top few inches of soil and are ravenous consumers of organic material. They are an annual species, dying over the winter, which means they grow faster and have much more energy to put toward reproducing. The egg cases are small and hard to find and jumping worms don’t need a mate! They can reproduce asexually and quickly, so it only takes one to create a new invasion. They leave behind castings very similar to coffee grounds when dry and ground beef when moist. An invasion of jumping worms can reduce leaf litter by 95% in one season, reducing 12 plus centimeters of rich, decomposing, organic material to an altered, bare soil.
This is a problem in many ways:
- There are fewer available nutrients and less protection for critters.
- There is no rich medium for seedlings to germinate and thrive.
- Less organic material decreases moisture retention and thermal protection to plants and animals.
- The coffee ground consistency of the soil makes it prone to erosion, depriving the ecosystem of even more nutrients.
- The altered soil is less favorable for the fungi, bacteria, and microbes that live within it, which forest trees have evolved to depend upon.
- They displace other earthworms, centipedes, salamanders, ground-nesting birds and disrupt the forest food chains.
- As the soil changes and native plants struggle to survive, invasive plants take over, further damaging the native habitat.
- As the understory and native plants disappear, deer are forced to feed on mature, native saplings.
- Soil invaded by worms could be releasing more carbon dioxide into the atmosphere.
In home gardens, disruption of the soil can diminish the growth of annuals, perennials, and turf grass.
- Because they are surface dwellers, they do not assist in pulling nutrients down.
- They do not create tunnel systems which aerate roots and help water to infiltrate the soil.
- They feed on the mulch gardeners use and have been known to eat young plant roots.
There is a lot to be learned about these invaders and much we don’t know. For instance, if Canandaigua’s steep, forest covered slopes become invaded with jumping worms, and the forest floor is left bare, what happens when the “coffee ground” soil erodes into the lake? How will those nutrients impact our water quality? What other cascading repercussions will we see? There are currently no effective means of removal once you have them, so the best answer is to prevent their spread.
Check out the Homeowner’s Guide for Asian Jumping Worms from the NY Invasive Species Research Institute for more information.
Article by: Sonya Carnevale, CLWA Outreach Committee Chair
Feature Image Courtesy of: University of Minnesota