Invasive, ravenous and hard to stop: Asian jumping worms on suburban gardeners’ radar

For years, the Arlington Heights Garden Club’s plant sale featured homegrown plants.

It was a way to make money and improve their gardens.

“Perennials, when they are happy, they tend to spread and expand over time,” said Pete Landwehr, chairman of the club’s annual sale. So members dug up and split plants, such as hostas and astilbes, and put a price tag on them.

But not this year. And you can thank the Asian jumping worm for the change.

The invasive worm was found last year in at least 12 members’ yards, including Landwehr’s compost bins. Wanting to be good nature stewards, the club decided this year to follow horticulture experts’ advice to slow the spread: Don’t share plants.

“In good conscience, we could not propagate these and spread them around,” Landwehr said.

So this year, the club is selling plugs it bought from a local nursery known for its native plants, plus plants that members grew from seeds and cuttings. It has about 1,400 plants available at the sale, which runs from 8 a.m. to noon Saturday, June 7, at the Arlington Heights Historical Museum, 110 W. Fremont St.

The worm’s story

The worm came to this country from East Asia in the late 1800s, likely on imported plants. There are three species, and they have nicknames, including crazy worm and Alabama jumpers.

They have spread quickly in the last 10 years and are now found in 38 states. (Their spread may have been aided by people who used them for bait or vermicomposting.)

It lives close to the top of the soil, favoring the cool, moist, dark habitat of leaf litter and mulch, according to Tricia Bethke, forest pest outreach coordinator at the Morton Arboretum in Lisle.

It eats faster than other worms, and it eats more. Experts at Cornell University Cooperative Extension say the worms strip forests of the layer critical for seedlings and wildflowers to grow, and where there is heavy infestation, the populations of native plants, soil invertebrates, salamanders, birds and other animals may decline. They can outcompete other worms that are useful for moving nutrients into and aerating soil.

They change the structure of the soil, making it blocky and friable, Bethke said; it will feel spongy and look like dried coffee grounds. Bethke said the soil then is more likely to erode.

The jumping worms reproduce faster than the other worms, and they don’t need a mate to do so. They reproduce asexually.

“Once you have one, you potentially have many,” Bethke said.

The University of Illinois Extension says there are confirmed sightings in 48 counties, including Cook and the collar counties.

What to do

Because the worms don’t like heat, they usually are not found in open spaces, such as corn or soybean fields, Bethke said.

How do you know if you have them? In late June and July, scratch the top of your soil or mulch, Bethke suggested. Jumping worms are noted for their wild movements (thus the name) when they are disturbed, thrashing around. They slither like snakes. They also have a different clitellum, which is a band around them, than other worms. It can be milky white, flush with their body, and completely encircle it.

You also can test by pouring a solution of one-third cup of ground mustard seed in one gallon of water, onto a 1-foot-square patch of ground, in mid-summer. The worms will come to the surface. That’s what Landwehr did; he suggested using fresh mustard to make sure the solution is especially irritating to the worms.

Getting rid of them is not easy. “Once you’ve got them, you’ve got them,” Landwehr said.

Buy heat-treated mulch. Bethke said most bagged mulch has been treated that way.

Experts also advise washing the roots of any plants you buy to get rid of eggs that may have been laid alongside the roots. Bethke suggested dipping the plants in buckets of water: Dip, shake. Move to a second bucket and repeat, then a third bucket.

There’s no known, proven chemical treatment to get rid of them, according to Bethke.

If you find them, grab them, bag them and put them in your trash. Or put them out in the hot sun, such as on a concrete sidewalk or a tray. They will disintegrate. “That sounds horrible, doesn’t it?” Bethke said. “Bake ‘em.”

The worms don’t survive the winter, but their eggs do. The egg sacs are small and resemble dried rice, according to Bethke.

Bethke said the worms don’t kill trees or bushes because they are not root feeders.

“Don’t panic. Just make sure you address what is going on,” she said.