Invasive Crazy Worms Are Snaking Their Way Across Maine

Feb 27, 2020

As Maine’s state horticulturist, Gary Fish is no stranger to calls from people reporting observations and asking questions about pests they have found on their property. But a call from a Patten resident last week about Asian crazy worms (Amynthas agrestis) really got his attention.

“I got the call from this person who has had [crazy worms] on his land for about five years,” Fish said. “But this time it appears he had gotten them with a load of manure.”

The caller, Fish said, reported that the manure had come in a dump truck with a non-working dump body, so he was forced to shovel the entire load out by hand. While doing so, he noticed an abundance of worms with each shovel load, but assumed they were garden-friendly earthworms

“Now that manure is spread all over his property and the worms are proliferating and he’s concerned they are crazy worms,” Fish said.

Cause For Concern

Without a clear photograph of the worms, Fish said he is unable to say with 100 percent accuracy if the Patten worms are crazy worms, but given the description provided by the landowner, he’s fairly confident then are. And if they are, there is reason for concern.

“I would not say we necessarily have a good handle of exactly how widespread they are in Maine, but I do know 13 new locations were reported over the past year.”

These sightings were reported to iMapInvasives, a national online database in which anyone can report and access locations of invasive species.

An invasive species in Maine, the aggressive Asian crazy worm, also known as “snake worms” and “Alabama jumping worms,” are not the friendly, soil-enriching earthworm gardeners and farmers welcome on their land. Rather, they are a species that spend their lives near the top parts of the soil where they voraciously consume organic material and mix up those top soil layers to the extent the dirt looks like coffee grounds.

The worms gained the “crazy” tag due to their ability to pop out of the ground or out from under the ground or patches of leaves like snakes.

The crazy worms are thought to have been in Maine since the late 1800s or early 1900s, Fish said. But it was not until 2012 that an established population of the worms was confirmed in the state when the Maine Coastal Botanical Gardens found some in a display of rhododendrons.

In 2014, a second population was confirmed at the Viles Arboretum in Augusta and several sites were found in Portland.

In ecosystems like Maine, plants and trees have evolved using nutrients broken down by native fungi — a very slow process allowing those trees and plants to access those nutrients. It can take up to three years for the fungi to break down a single leaf. A crazy worm can do it in three weeks. That means the nutrients are depleted long before the trees or plants can use them.

“We see them cause so much disruption to the soil and around roots that they kill plants and trees,” Fish said. “They deprive the plants of the organic nutrients that are slowly released in the natural decomposing process of leaves and other duff on the forest floor.”

Born Pregnant

Once in a garden, on a golf course, a homeowner’s lawn or anywhere else anything is growing, the crazy worms create a similar path of destruction. And it only takes one crazy worm 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 at this point to eradicate them.

“If you know you have them and where they are, you can try digging them up and disposing of the soil,” Fish said. “But if they have already laid cocoons it’s going to be hard getting rid of them all [and] for now it appears once you have them you are stuck with them.”

Disposing of soil in a manner that will destroy the worms is no simple task, Fish said. The only safe way is transporting it to a facility in which it will be treated in a way that kills the worms and their eggs. Here in Maine, that means checking with the Maine Department of Environmental Protection to find a location.

Prevention

To prevent an infestation, Fish recommends knowing where any new soil, compost or manure coming onto your land originated and ask the supplier if they have a history of crazy worms.

“Like with the gentlemen from Patten and the manure, these worms can be passed around in all kinds of soil amendments,” Fish said. “By asking [suppliers] about the worms, it will also help raise general awareness of the species.”

Fish also encourages purchasing new plants with bare root stock, only purchase potting soil you know has been sterilized and never use crazy worms as fishing bait. But there are still risks, he said. All it takes is a small tear or hole in a bag of clean soil for a crazy worm to gain access and lay eggs.

Crazy worm control is receiving increasing attention nationwide, Fish said, with researchers from New England to California working to develop products and methods that will kill the worms and their cocoons. At the University of Vermont, Dr. Josef Gorres is looking at the worm’s impact on the state’s maple sugar industry — research that could have applications to Maine’s maple sugar economy.

In the meantime, Fish is hoping Mainers will keep their eyes peeled for evidence of crazy worms and report any suspected sightings to his office at the Maine Department of Agriculture, Conservation and Forestry by emailing horticulture@maine.gov.

This story appears through a media sharing agreement with Bangor Daily News.