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There’s an invasive earthworm wreaking havoc in northern woodlands – it’s called the Crazy Worm. Crazy worms disrupt the natural decomposition of leaf litter on the forest floor. They turn good soil into grainy, dry worm castings that understory plants can’t grow in. They can also show up in urban parks and back yards, and are aggressively spreading to more states.
Larry Caplan is an extension horticulture educator at Purdue University. He says it’s hard to tell crazy worms apart from regular earthworms – until you grab one.
"There are some minor anatomical differences, but to be perfectly honest, I would even need a picture in front of me to be able to tell them apart. But mostly, it’s the behavior. While all earthworms will kind of squirm around trying to get out of your hand if you pick one up out of the ground, the crazy worms will be really thrashing about wildly," says Caplan. "It’s almost like it’s bouncing around, or jumping."
They have a voracious appetite and life cycle, which gives them a competitive edge. In areas with crazy worms, there are no other species of earthworm.
Caplan says Departments of Natural Resources want you to be aware of this growing issue, and do what you can to not spread them.
"If you are sharing plants with other gardeners, you might want to wash the soil off the roots to make sure you’re not moving earthworms and other critters with your plant," he says. "When you buy landscape plants, make sure that you’re buying from reputable nurseries and garden centers, and make sure that if you are using compost, that it’s been completely composted up to the appropriate temperatures."