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If you spot jumping worms in your garden, handpick and destroy them. The invasive pest can wipe out large quantities of organic material in the top layer of soil.

Another invasive pest is making its presence known in Lancaster County — the jumping worm (Amynthas spp.), sometimes called crazy worms or snake worms. This pest negatively impacts soil and threatens to displace the common earthworm or nightcrawler (Lumbricus terrestris).

Even though nightcrawlers are not native, their presence is generally a good thing for gardeners. Their tunnels increase soil’s ability to hold air and water, and their casts (waste material) help distribute organic material through the soil.

On the other hand, jumping worms are such voracious feeders that they can wipe out large quantities of organic material in the top layer of the soil. Their casts, which look like dry coffee grounds, break down so slowly that they are not beneficial.

How do I know if I have jumping worms?

Granular soil is the most common sign of jumping worms. Then, if you dig a few inches into the soil, you may encounter the jumping worms themselves. They will writhe and move quickly, like snakes. A close look will reveal that the jumping worm’s clitellum (band) completely encircles its body, whereas a nightcrawler’s clitellum is raised and has a break in it.

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If you spot jumping worms in your garden, handpick and destroy them. The invasive pest can wipe out large quantities of organic material in the top layer of soil.

What can I do to control jumping worms?

If you do not have jumping worms in your garden now, the best defense is to avoid importing them.

Jumping worms overwinter in the soil as tiny egg-filled cocoons that are too small to see easily, so just looking for worms in new plants and soil isn’t enough to keep them out of your garden.

For purchased or gifted plants, carefully look for the telltale coffee-ground-like soil, and, if present, remove the plant from the pot, throw away (do not compost) the soil, and wash the roots in a sink before planting outdoors. Also, only purchase mulch or compost that has been heat treated. Make sure worms you purchase for fish bait or vermicomposting are not jumping worms.

Research is underway on control methods for jumping worms. For now, here are suggestions for reducing an infestation:

• Handpick and destroy them. A drench of 1/3 cup dry mustard to a gallon of water poured on the ground will irritate jumping worms and bring them to the surface.

• Solarize the soil to destroy the cocoons. In late spring or early summer, cover soil with clear plastic for several days. Temperature should be over 104 F under the plastic fo• r at least three days.

• Incorporate diatomaceous earth into the soil where jumping worms are active. This may have a detrimental effect on them but will not harm beneficial nightcrawlers.

• Finally, if you suspect that your garden has jumping worms, be extremely careful about sharing plants. Wash the roots and replant in purchased, bagged soil.

While gardeners through Pennsylvania have been battling jumping worms for several years, the master gardeners of Lancaster County have just begun to receive reports of them from residents.

For more information, see “Look Out for Jumping Earthworms,” online at extension.psu.edu/look-out-for-jumping-earthworms.

For help identifying jumping worms or other garden pests and diseases, contact Lancaster County Master Gardeners at LancasterMG@psu.edu or 717-394-6851.

Lois Miklas is an area coordinator, for several counties including Lancaster, for the Penn State Extension Master Gardener program.

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