New invasive species, crazy worm, found in UW Arboretum

Asian earthworm found in fall 2013, eggs survived winter, officials say
New invasive species, crazy worm, found in UW Arboretum
Crazy Worm

Wisconsin’s newest invasive species, the Asian crazy worm, has been found for the first time on the University of Wisconsin campus, according to a release.

The UW Arboretum is the first confirmed site for Amynthas agrestis, an invasive worm believed to have come to the United States from its native Japan and the Korean Peninsula with plants imported for landscaping, officials said.

“Amynthas was listed as a prohibited species under Invasive Species Rule NR 40 since its adoption in 2009, because we knew their introduction into our state poses a huge threat to the future of our forests,” said Bernie Williams, invasive species specialist in forest health at the DNR.

Williams and arboretum staff members found the worm in the fall of 2013, according to the release.

Arboretum ecologist and Research Program Manager Brad Herrick said they believe the worms’ egg cocoons have survived the harsh winter.

“They are here, but we are still trying to get a handle on the extent of their distribution at the arboretum,” Herrick said in the release. “While we do that, we’re instituting some best management practices – cleaning boots and tools, washing vehicles – and doing our best to stay clear of the areas where we have found the worms.”

In most of the state Amynthas is not the only invasive earthworm, according to the release. European species introduced by the first settlers across the state can damage natural landscapes, but those species rarely reach numbers like the Asian species.

“Amynthas’ life cycle is completely different from European species of earthworms,” Williams said. “It breeds en masse, and is constantly dropping cocoons. Where the cocoons hatch, at the soil surface you’ll see what looks like small filament hairs moving in the soil surface in large numbers.”

The grayish Amynthas is darker in color than pale, pinker European earthworms, grows to 8 inches long, and has earned common names like crazy worm, snake worm and Alabama jumper by flopping and wriggling when handled, according to the release.

The crazy worms mature in just 60 days, allowing populations to double during Wisconsin’s warm months, and can reproduce without mating, officials said. When numbers spike to the levels of infestation, Amynthas can eat all of the organic matter at the soil surface, exposing the ground to erosion.

“That’s our concern in the arboretum and anywhere they turn up,” Herrick said. “Our native plant communities developed without the presence of all these hungry worms. The Amynthas eat so much that they take away the spongy, surface organic layer that those plans need for nutrients.”

Herrick said the Arboretum, DNR and researchers will be testing potential control techniques, but careful cleaning of equipment and quarantine is their first line of defense.