What They Are and Why They're Different

Forget the earthworms you dug up as a kid. The Asian jumping worm (Amynthas agrestis and related species) is a different animal entirely.

These things grow up to six inches long, thrash like snakes when disturbed, and can literally launch themselves a foot off the ground. According to Mac Callaham, a USDA Forest Service researcher who studies soils, the worms got their name from that violent, erratic movement — and it's not just a party trick.

They're smooth, dark gray or brown, with one dead giveaway: a milky white or light gray band — called the clitellum — that sits flush with the body and wraps completely around it, per the Colorado Department of Agriculture.

What They Actually Do to Soil

Normal earthworms help aerate soil and break down leaf litter at a manageable pace. Jumping worms do the opposite. They devour organic matter and leaf litter so aggressively they strip the surface layer that native plants depend on to survive.

The Colorado Department of Agriculture calls it a "nutrient-poor paradox" — the worms break nutrients down faster than plants can absorb them. What's left looks like dry coffee grounds. The soil becomes granular, dries out faster, and is effectively useless for growing most plants.

They don't burrow deep like European nightcrawlers either, so there's ZERO benefit of soil aeration or water infiltration. They only destroy. They also displace native species that depend on intact soil ecosystems, according to the National Invasive Species Information Center.

38 States and Counting — Including Colorado Just Confirmed

Asian jumping worms first arrived on U.S. shores in the late 1800s via potted plants on ships from East Asia, according to the National Invasive Species Information Center. They've been quietly spreading ever since.

As of now, they've been confirmed in 38 states — from California to New York, New Jersey, and Connecticut, according to the NY Post citing agriculture experts. The Midwest and Northeast have been hit hardest, but the spread isn't stopping.

Colorado just confirmed a detection in Denver's Hilltop neighborhood in October 2025, per the Colorado Department of Agriculture. Reports had already been coming in from Boulder to Castle Rock before that official confirmation.

Two main paths explain their rapid spread. First, the horticultural trade — nurseries unknowingly sell infested plants and soil. The New Jersey Department of Environmental Protection has noted the worms are "abundant in both field and container stock" at nurseries. Second, anglers dump them as fishing bait, per the National Invasive Species Information Center.

They're literally being handed out at garden centers and bait shops.

No Eradication. None.

Once established, there is no effective method to eradicate these worms. The Colorado Department of Agriculture states this plainly. So does FOX 10 Phoenix in its reporting.

Prevention is the only tool available. That means:

• Don't move soil, mulch, or plants from infested areas
• Clean gardening tools before moving between sites
• Buy heat-treated mulch when possible
• Report sightings — Colorado has an official Jumping Worm Reporting Form through the state's Department of Agriculture

Minnesota took one of the more serious regulatory steps, with the Minnesota Department of Natural Resources classifying jumping worms as a prohibited invasive species effective July 1, 2024, making it unlawful to possess, import, purchase, or transport them without a permit, according to the National Invasive Species Information Center.

Most states have NOT done this. That's a failure worth naming.

What Regulators Are Getting Wrong

The NY Post noted something that deserves more attention: few states officially recognize jumping worms as invasive, even though they clearly are. The reason? Regulatory attention is monopolized by insect pests and invasive plants. Worms fall through the cracks.

This is a classic government bureaucracy failure. The threat is documented, the science is clear, the spread is measurable — and most state agencies are doing next to nothing. Meanwhile, every nursery sale and fishing trip potentially seeds a new infestation.

The USDA Forest Service has researchers like Callaham who understand the threat. The science is not in dispute. The policy response is just absent.

What This Means for You

If you garden, landscape, or own property in any of those 38 states — which is most of the country — this is a real and growing problem. Confirmed infestations are already degrading soil in backyards, public parks, and forests across America.

The worms are annual — adults die at first freeze — but their cocoons survive winter and hatch the following spring, per the Colorado Department of Agriculture. The infestation resets and resumes every single year.

No pesticide has been approved, no biological control has been deployed, and no federal eradication program has been funded. The government's current answer is essentially: don't spread them further and hope for the best.

Check your soil. Know what you're buying at the nursery. And if you see coffee-ground dirt writhing with snake-like worms — report it.