A foreign worm with a big appetite has burrowed into the soil of the University of Wisconsin-Madison Arboretum, officials said Tuesday.
The Asian crazy worm was discovered last fall in the arboretum, and the species survived the harsh winter.
Officials say it’s the first time the species has been seen in Wisconsin, although it’s been in the East and Southeast U.S. for 50 years.
Scientists are nervous about how the invasive worm – scientific name Amynthas agrestis – could affect Wisconsin’s forests.
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“They basically consume the forest floor,” Brad Herrick, arboretum ecologist and research program manager, told the Wisconsin State Journal. “They often do it quite quickly.”
The 8-inch worms reach maturity in just two months and create offspring without mating. When infestations happen, the worms devour nutrient-rich soil at the forest floor. Erosion sets in, making it harder for native plants to survive. In their place, pesky invasive plants can grow.
The worm is called “crazy” because it flops and wriggles vigorously when handled. Arboretum employees found it by chance last October while leading a field trip to show visitors nightcrawlers – also invasive worms from Europe that have been here for centuries. Preparing to pour mustard water on the soil, the preferred method of drawing crawlers to the surface, they were met with a surprise.
“Lo and behold we found another worm that until that moment we didn’t believe was in the state,” Herrick said.
Bernie Williams, an invasive species specialist with the Wisconsin Department of Natural Resources, was on the trip and confirmed the mystery worm’s identity.
The worm is darker in color than the pale and pinker European earthworm, the common worm found all across the state. It also has a smooth and flat band of milky white, unlike the raised, ridged band found on European earthworms.
It is believed the crazy worm first came to the U.S. from its native Japan and Korea in the soil of plants imported for landscaping. Wisconsin’s worms likely hitched a ride aboard some nursery plants headed here from the eastern U.S., Herrick said.
Boots, tools and vehicles at the arboretum are being washed regularly to keep the worm from spreading, and employees are avoiding areas where the worm has already been found.