Jumping Worms: What They Are and Why NH Gardeners Should Be Concerned

Jumping Worms in NH Gardens

If you’re a gardener on the New Hampshire Seacoast and care about the health of your soil and plants, there’s a new threat you should be aware of: jumping worms. These invasive pests are spreading quickly across the region and leaving behind damaged gardens, degraded soil, and frustrated homeowners. If you’ve noticed strange soil texture or rapid changes in your garden, it might be time to consider the possibility of a jumping worm infestation.

What Are Jumping Worms?

Jumping worms are invasive earthworm species native to East Asia, including:

• Amynthas agrestis

• Amynthas tokioensis

• Metaphire hilgendorfi

They get their name from their signature movement—when disturbed, they thrash violently in a way that looks more like a snake than a worm. This “jumping” behavior is one of the easiest way

Jumping Worm Traits to Watch For

They also have a few other noticeable traits:

• Appearance: Smooth, glossy gray or brown with a metallic sheen

• Clitellum: A milky white, flat band that wraps evenly around the body (unlike the raised band in common earthworms)

• Soil Clues: Leave behind a loose, crumbly layer of castings that resemble dry coffee grounds at the soil surface

These signs often appear in garden beds, under mulch, or near compost piles—common places where jumping worms in garden soil thrive. Many gardeners first detect them while preparing new beds or turning over soil in early spring.

Why They’re a Problem

Unlike helpful native earthworms, jumping worms are destructive. They consume organic matter rapidly, leaving behind degraded soil with poor structure. This kind of soil holds less water and fewer nutrients, making it difficult for plants—especially perennials and native species—to survive. Gardeners dealing with soil damage from jumping worms often see their plants suffer despite regular care and watering.

Over time, this disruption to the soil profile can affect everything from plant roots to the beneficial fungi and microorganisms that support a healthy landscape.

The consequences don’t stop there. Jumping worms outcompete native earthworms and insects, which in turn affects birds and other wildlife that depend on a balanced soil ecosystem. Even more concerning is their reproductive strategy. These worms don’t need a mate—just one adult can lay hundreds of tiny cocoons each season, making them extremely hard to control once established. This is one of the reasons jumping worm populations in NH are growing so quickly.

How They Spread

One of the most troubling things about jumping worms is how easily they spread. Their cocoons are about the size of a sesame seed, making them nearly impossible to spot. These cocoons can survive New Hampshire’s winters and are often moved unintentionally in:

• Potted plants

• Mulch and compost

• Soil from garden centers or landscaping jobs

• Fishing bait discarded in natural areas

This is why it’s so important to avoid unknowingly spreading jumping worms in New Hampshire by checking materials before moving them to a new site.

What You Can Do

Preventing the spread of jumping worms starts with awareness. Here’s what you can do as a homeowner or gardener:

• Inspect soil and mulch before bringing it onto your property, especially if it's from an unfamiliar source

• Avoid moving or sharing soil and plants from areas that may be infested

• Never dump fishing bait in natural environments or garden beds

• Use solarization for small infested patches—cover soil with clear plastic in full sun for several weeks

• Try a mustard flush: Mix 1/3 cup of mustard powder with a gallon of water and pour it over the soil to bring worms to the surface for removal

While there’s no single solution, early detection and physical removal are currently the most effective options for managing jumping worms in garden soil. Many home gardeners in NH are now monitoring for signs of invasive worms as part of their seasonal maintenance routines.

Prevention for Seacoast Gardeners

For Seacoast Gardener clients and local homeowners, we recommend a few best practices. Always clean tools and boots between properties, especially if you work in multiple gardens. Don’t share or transplant plants with unknown soil. And when purchasing mulch or compost, ask your supplier if they test for jumping worms. These small steps can help protect your landscape—and the wider local ecosystem—from a serious and fast-spreading threat.

At Seacoast Gardener, we’re committed to helping homeowners protect their gardens from invasive threats like jumping worms. Our team stays informed on the latest prevention and control strategies, and we can help you identify issues early and take action to preserve the health of your landscape.

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