A voracious worm that’s born pregnant and difficult to kill is growing in numbers around the state — and it has Maine’s biologists and gardeners worried.
The Asian jumping worm — also called a crazy or snake worm — has been in Maine for more than a century. They are not soil-enriching earthworms, and gardeners and farmers do not welcome them on their land.
Rather, they are a species that spend their lives near the top parts of the soil where they consume organic material and mix up those top soil layers until the dirt looks like coffee grounds.
A population boom of the species is a big problem in a place like Maine. The plants and trees here have evolved using nutrients broken down by native fungi. It’s a very slow process that takes years and allows those trees and plants to access those nutrients, but when a jumping worm does it quickly the nutrients are depleted long before the plants can use them.
Just three years ago the worms were confirmed in nine locations among seven counties in the southern tier of the state. Since then, they have expanded into 13 counties and there is indication a 14th is about to be added to the list.
“All of a sudden, this year there are a lot more worms being sent in for identification,” said Jim Dill, pest management specialist at University of Maine Cooperative Extension. “Last year we got a dozen in total, and this year we are getting two or three a week.”
The worms gained the “crazy” and “jumping” tags due to their ability to pop out of the ground or from under patches of leaves like snakes.
“If you touch one they really do go crazy jumping and wriggling around,” Dill, who recently had to recapture a worm making a mad dash across a laboratory table, said.
Just last week, a colleague of Dill’s discovered a number of jumping worms under a log in Penobscot County, which so far had remained off the list.
People are reporting finding hundreds and even thousands of the worms in their gardens this year. With that rate of expansion, the worm is set to have a big impact, experts say.
“Research out of University of Vermont is showing what effect [the worms] are having on sugar maples and the spring ephemeral plants,” Gary Fish, Maine State horticulturist, said. “That would have a cascading effect on the birds and other animals that depend on those.”
Once they get in a forest setting, garden, golf course, homeowner’s lawn or anywhere else things are growing, the crazy worms create a path of destruction. And it only takes one egg or cocoon to get the ball rolling.
Crazy worms reproduce through parthenogenesis, meaning embryos are produced and develop without being fertilized by sperm. In short, they are literally born pregnant, and once established there is not much that can be done to eradicate them.
The worms and their egg cases, which are almost impossible to see, spread very easily through the transport of soil or compost and even on dirt sticking to firewood that is moved to a new location.
“Those cases are easily transported on plant material,” Dill said. “You can go to a nursery, bring home just a couple of egg cases and there you go.”
With the crazy worms spreading just as quickly nationwide, researchers at Cornell University, Yale University and University of Vermont are turning their attention to the potential harm they can cause outside of forestland.
A jumping worm working group has also been formed to study the worm’s dangers here in Maine.
Their wiggly behavior also makes them a favorite bait for fishers in Maine, Dill said. He worries that live jumping worm bait may be getting tossed into the woods.
“We really don’t know a lot right now of their impact on vegetables or ornamental plantings,” Fish said. “What we do now is that they can eat up all the organic materials and starve out some plants.”
There are many theories on how to eradicate jumping worms, but Fish said none are reliable. He discourages a full-scale chemical, biological or physical assault on the worms because earthworms and other beneficial species could become collateral damage.
“I have a feeling we are going to be seeing more of them around on a regular basis,” Fish said. “We really need to wait for the research to see if or how big of a problem this is going to be.”
