Jumping Worms Alert

It’s often a surprise to gardeners, who may think of earthworms as key players in their garden soils, that there are almost no native species of earthworms in the Northeast. Here in the Hudson Valley, earthworms were wiped out in the last glaciation, over 10,000 years ago. The earthworms we're most familiar with were introduced from Europe and have since spread to become present throughout the Hudson Valley. 

In recent years, new invasive earthworms from Asia have arrived in the Hudson Valley. Commonly called jumping worms, or “snake worms” (Amynthas and Metaphire spp.), these worms have the potential to wreak havoc on our gardens and severely degrade our natural ecosystems, particularly forest soils. 

Jumping worms can be identified by their clitellum (central band), which is nearly flat and very pale, as opposed to the more raised and darker band on most European earthworms. They also thrash violently when disturbed. Photo: Juan Cepeda Espinosa via Wikimedia Commons

How do I know if I have them? 

Jumping worms themselves are most easily identified in midsummer through early fall, when the worms are in their adult stage. The worms overwinter as tiny cocoons (eggs), and don’t mature until late June or early July in the Hudson Valley. Adult worms “jump”, or thrash, when disturbed; but the best indicator of their presence is usually the soil itself. By late June, the worms have hatched and are maturing, and their voracious feeding (and pooping) creates a distinctive “coffee grounds” soil texture.

Jumping worms leave behind a characteristic soil texture, marked by small granular balls of defecated soil called castings.

Why are they a problem?

Jumping worms reproduce asexually and very quickly, so just one worm can quickly create an invasion. Mature worms eat voraciously. They inhabit just the top few inches of soils and can quickly consume organic matter, damaging soil structure, fungal networks, and nutrient cycles. In gardens, they consume plants’ fine roots and can compromise germination of late season seed-sown crops. They are particularly destructive in forest soils, where they can eliminate leaf litter layers, removing habitat for insects, amphibians, and other forest life. Their presence compromises the germination of native plant seeds, and paves the way for invasive plants like Japanese stiltgrass, Japanese barberry and garlic mustard. 

How do they spread?

Once a single egg is introduced to the soil, jumping worms will rapidly invade an area, multiplying and laying countless eggs. Eggs can be spread from the source to other properties via muddy boots, topsoil or compost deliveries, and in the soil of potted or transplanted plants. Unfortunately, the nursery trade is a major source of jumping worm spread. Jumping worms have been found in plants from many nurseries throughout the Hudson Valley.  

Jumping worms are currently present in some natural areas in the Hudson Valley, but other places are still uninvaded and deserve to be protected. Once jumping worms have arrived, there is no known consistently effective treatment to eliminate them. If you are planting in an area where jumping worms are not yet present, especially if you are adjacent to a woodland, we strongly recommend doing everything possible to avoid bringing them in. 

What can I do to prevent their spread? 

• For maximum jumping worm prevention, plant seeds or bare root plants only. You can also grow your own plants from seeds, indoors in sterile potting mix. See our Nursery List for bare root plant and seed sources [LINK].

• Do not purchase soil, compost, mulch, or potted plants from a supplier that has jumping worms onsite. Ask growers whether they have found jumping worms in their pots. If purchasing plants in the late summer for fall planting, inspect the pots for adult worms and worm castings (in the spring, only the tiny eggs will be present). Approach plant swaps with caution— and ask if worms are present in the plants’ original location. 

• Clean all footwear and tools (from trowels and shovels to large farm equipment) thoroughly before leaving anywhere that jumping worms are present, and before entering anywhere that they are not present, such as a healthy forest.

• Get to know your local nursery and advocate for jumping worm-safe growing practices, such as growing in sterile potting mix, keeping pots on elevated tables, and offering bare root options.

What do I do if I have them already? 

• Minimize the spread of worms from your property to others’. Don’t give away transplants, and clean your garden boots and tools before heading to other properties. If your infestation is still small, keep it that way -  take care not to move soil or plants around even within your own property.

• Minimize your use of mulch. Jumping worm populations grow most rapidly under thick mulch layers, including wood chips, hay, and leaves. Consider skipping the mulch to discourage worms, and give native plants a chance to re-seed throughout your garden!

• Try a soil drench using a saponin-based fertilizer, like tea seed (Camellia) meal. Some sources suggest this can effectively kill adult worms. It’s best applied in midsummer when worms are maturing but have yet to lay eggs.

Consider a deer exclosure in your woods. Scientists have identified a link between deer overpopulation and earthworm abundance - including both European earthworms and jumping worms - in forests. The mechanism for this relationship is still unclear, but it’s been repeatedly shown that when deer are excluded from a large forest area by a fence, worm populations gradually begin to decline.