Tricounty News

A foreign species among us: earthworms are not helpful

Gardeners, anglers and other outdoors enthusiasts are likely to encounter earthworms. Minnesota earthworms are exotic species from Europe and Asia. Aside from their use for bait and composting, most people don't know the purpose of earthworms. A group of scientists think they should.  Minnesota has no native earthworms, angle worms or night crawlers. Those that have been brought to our state harm native forests, reduce wildflower populations, and may cause increased erosion and reduced water quality. Research conducted by staff and graduate students from the U of M Center for Hardwood Ecology is documenting the harmful effects of exotic earthworms. "Our research is verifying what others have observed in Minnesota and Wisconsin forests," said Cindy Hale, who has been doing worm research for several years. "The worms are not as good as we were all led to believe."  Steve Mortensen, biologist from the Leech Lake Reservation, added, "We have observed the leaf litter in forests disappearing and along with it the native wildflowers, ferns and tree seedlings. Once earthworms have invaded, they cannot be removed." Experts encourage anglers and others not to spread earthworms to new areas. DNR Exotic Species Program Coordinator Jay Rendall suggests disposing of unwanted earthworms used as bait in the trash and not at boat landings, roadsides or in the woods. It is also possible to unknowingly spread the worms by moving soil, compost and mulch, even in small amounts, from one place to another. For more information about earthworms, visit the DNR Web site at or visit Minnesota worm watch at A "Contain those Crawlers" poster is also available from the DNR for use in schools, nature centers and outdoor-related retail outlets. To obtain a copy, call toll free (888) 646-6367.