Patricia Weaver was digging up perennials in her yard in Terre Haute, Indiana, in August when she uncovered a mass of dark-colored, aggressively thrashing earthworms.
“I moved a plant off to the side and saw these things just jumping around,” Weaver said. “They were just squiggling everywhere, and I was like, ‘What the heck are these?’”
The worm-infested soil had the consistency of coffee grounds, and its covering of leaf compost was gone. Weaver picked the worm out of the soil.
“I tried to feed them to my chickens, but they were freaked out by them jumping,” Weaver said. “I stuck them in a bucket of water and let them drown.”
A Purdue Extension specialist in town, Tabitha Flinn, confirmed they were invasive Asian jumping worms. More than 500 had invaded Weaver’s yard, presumably after arriving in the leaf compost.
Asian jumping worms, also known as Alabama jumpers or crazy snake worms, were discovered in Wisconsin in 2013, said Steve Yaninek, Purdue Extension invasive species specialist.
Since then, they have spread to most of the Midwest, including Indiana. They thrive in forest understories where it’s shady and there’s a lot of organic matter to eat. But because they are spread by human activity, they are mostly found in urban areas.
“They’re more likely to be in gardens with a convenient forest nearby, like a park,” said Bob Bruner, 42, Purdue Extension exotic forest pest specialist.
Jumping worms can be distinguished from night crawlers — the good earthworms — by their quick, violent movements and the white band fully circling their bodies.
“Jumping worms don’t aerate the soil like night crawlers. They live in the first few inches and eat all the organic matter. Their castings, or waste, have low nutritional value,” Bruner said.
“They leech out the nutrients, grow more quickly, and outcompete the other worms,” Yaninek said.
What it does, besides jump
An infestation of jumping worms makes the top layer of soil barren and crumbly. Plants fall over because they can’t root properly, or they die of malnutrition. The soil can’t be rejuvenated with fertilizer if the worms are still present. They’ll just be grateful for the extra food.
The presence of jumping worms hasn’t yet been reported in Tippecanoe County. Jumping worms have been confirmed only in Vigo and Marion counties, but there have been unconfirmed reports filed across the state.
Fortunately, the spread is slow, because jumping worms move long distances only with human interference, Bruner said. They can hitch rides on dirty equipment or bags of compost. Jumping worms are marketed as bait, because their movement style is good for attracting fish.
“We don’t know how many there are, we only have sighting reports,” Bruner said. “But they reproduce quickly. Adults are popping up early this year.”
Jumping worms lay their eggs in winter. The eggs hatch when it’s warm enough, usually in April. If they’ve infested a warm, bacteria-rich compost pile, they can hatch months ahead of schedule. Early hatching means more generations each year, and therefore, more jumping worms.
The worms become adults in 60 days, lay eggs and then die.
Yaninek said night crawlers are also not native to the United States. They were carried in plants brought over with settlers. Unlike jumping worms, they adapted well to their new environment without disrupting it. A species is considered invasive when it causes ecological harm.
How to fight them
There are ways to cure your garden and stop the spread of jumping worms. Weaver regularly rakes up her yard’s soil, picks out the worms and kills them.
“If I don’t get all of them, they’ll get under the cover of the wood chips,” Weaver said. “They scooch off really fast.”
If that fails, Weaver mixes dried mustard powder with water and uses that to water her yard. Mustard causes a stinging sensation that drives worms out of the soil so they can be easily removed. Weaver said this method, theoretically, won’t harm night crawlers because they burrow deeper.
To kill any jumping worms that might be present in pre-purchased soil, Bruner recommends placing it in a plastic bag in direct sunlight until the interior of the bag reaches 105 degrees. Gardeners should verify the worms are dead.
A long-term cure for jumping worms may be on the horizon.
Yaninek studies biological control, a method of invasive species management that uses “good insects” to control “bad insects.” It was first used in the 1890s, when the cottony cushion scale, an invasive insect, was destroying U.S. citrus crops.
Biologists introduced the vedalia beetle, a species native to Australia that eats all stages of the cottony cushion scale, to the U.S. citrus crops. After several years, Yaninek said citrus production doubled.
“It was a phenomenal success,” Yaninek said. “It kicked off the whole movement of biological control.”
Biological control was used in the 1980s to control the apple ermine moth, an invasive pest whose caterpillars defoliated apples trees. A parasitic wasp from Eurasia was introduced to the northwest U.S.
“It reduced the ermine moth so that it was no longer a pest at all,” Yaninek said. “There’s just enough of them to maintain the predator population.”
Theoretically, biological control could be used against jumping worms, but that still requires years of research.
“There’s not a lot of earthworm pest management,” Yaninek said. “With Asian jumping worms, we don’t know where to start.”
“You have to work backwards from where the pest was introduced from,” Yaninek said. “Look at what their natural predators are and find an agent that can satisfy quarantine requirements.”
Quarantine requirements are a set of rules and regulations set by the U.S. Department of Agriculture on species people want to bring into the country.
“A biologist would have to prove that a predator has a precise, limited, target effect,” Yaninek said. “Meaning it doesn’t eat good worms.”
In the meantime, Yaninek said to prioritize growing native plants in your garden and never bring plants from abroad.
If you believe you have found a jumping worm in your garden, Bruner said you should report it to 1-866-NOEXOTIC or file a report at EDDMapS.org/indiana and attach a very clear picture.
“Be alert to what looks different in your neighborhood,” Yaninek said. “Citizens alert biologists.”
