Amynthas agrestis, an invasive earthworm from temperate regions of Asia, was found in limited areas near the Visitor Center in fall 2013. The Arboretum is one of the first sites where an Amynthas population has been documented in Wisconsin.
Amynthas spp. have been found in the eastern U.S. for several decades. They are significantly more destructive and aggressive than European earthworm species. Amynthas alters soil structure and chemistry dramatically, leaving a distinctive grainy soil full of worm castings (feces), and damages forest understory habitat. The presence of Amynthas may facilitate spread of invasive plant species.
The worm reproduces without mating (parthenogenically) during its entire active season and matures in 60 days—populations grow rapidly and outcompete other species. The best time to begin seeing them is in late June and July as the first hatchlings mature. Heading into fall their population can double and may reach damaging levels.
Amynthas was likely introduced accidentally. The Arboretum is facilitating much-needed research as well as public outreach and education. Staff are following DNR best management practices to limit spread of the worm. The worm has also been found elsewhere in Madison.
Amynthas species are prohibited under Wisconsin’s Invasive Species Rule NR40—it is illegal to possess, transport, or transfer, or introduce them in the state.
For more information about Amynthas worms, how to identify them and what to do if you think you find them, download our Amynthas information sheet (PDF).
If you find or suspect you have Amynthas on your property, please email Bernie Williams, Wisconsin DNR, Invasive Plants and Earthworms Outreach Specialist
Could a gardener’s friend be an ecosystem’s foe? 9/3/14, Water Sustainability and Climate project blog post about UW research taking place at Arboretum
Hungry, invasive ‘crazy worm’ makes first appearance in Wisconsin, 7/15/14, Chris Barncard, UW–Madison
Larry Meiller Show, 6/25/14, with Bernadette Williams and Kelly Kearns, Wisconsin DNR
LAST UPDATED 9/22/14