Mystery Snails

Mystery Snails

Two types of mystery snails will be discussed here – Chinese mystery snails (CMS), and banded mystery snails (BMS).

Where are mystery snails from and how did they get here?
CMS are originally from Asia. They were brought to California as a food source, and spread to other parts of North America from there, likely as an aquarium release.
BMS are originally from the southeastern United States, usually in the Mississippi River system. It is popular in aquariums, and is most often spread through aquarium dumping.

CMS (left) and BMS (right)

Mystery snails get their “mysterious” names because they give live birth to fully developed young – unlike native snails that lay eggs. It takes only one impregnated snail to start a new colony

How do I identify mystery snails?
CMS are identified primarily by the size of their shell – they grow to be much larger than native snails. They are round and apple-shaped.

CMS are apple-shaped

An example of how large CMS can grow

BMS are most easily identified by the horizontal stripes on their shells.

Stripes on a BMS shell

Please contact our Water Program Coordinator if you think you have found mystery snails.

How do mystery snails affect Wisconsin water bodies?
Both CMS and BMS are prolific reproducers and can form dense aggregations. They compete with native snails, and can be a nuisance on beaches and around docks.

When mystery snails invade a system, you can quickly pick up hand fulls of shells from shallow lake areas


What can be done once mystery snails enter a Wisconsin water body?
At the moment, there are no known methods of removing mystery snail populations. If your lake group chooses to hand harvest mystery snails, this activity must be conducted on a very large scale, and completed several times within a season, each year, in order to decrease snail populations. Harvested snails should never be thrown in another lake, or even onto land in case an animal transports the snail. Dispose of snails in a tied garbage bag, or let them dry out in a bucket for several weeks before disposing of the snails. Mystery snails can live outside of the waters for up to two weeks.

Additional Resources

Manitowish Waters Lakes Association

Wisconsin DNR Aquatic Invasive Species

Citizen Lake Monitoring Network: Get Involved!

Great Lakes Indian Fish & Wildlife Commission (GLIFWC) Invasive Species Area Maps

US Geological Survey Invasive Species Research

Vilas County Land and Water Conservation Department

Invasive Plants Association of Wisconsin



Available for loan.

Lake Plants You Should Know- A Visual Field Guide. University of Wisconsin- Extension.

Aquatic Plants of the Upper Midwest- A Photographic Field Guide To Our Underwater Forests.Written by: Paul Skawinski.

Through the Looking Glass- A Field Guide to Aquatic Plants. Written by: Susan Borman, Robert Korth, and Jo Temte.

Saving Our Lakes and Streams. Written by: James A. Brakken.

Your Help Is Needed

Curly leaf pondweed has been found in the Manitowish Waters Chain. Please keep your eyes open and let us know if you see this aquatic invasive plant along your shorelines or docks. Additionally, please check your boats and props to prevent the spread!

Citizen AIS Lake Monitoring

Join a crew to search for suspicious-looking species (plant or animal). Keep your eyes peeled and report any sightings to us.

Clean Boats Clean Waters

Educate boaters at landings and inspect boats and trailers.

Volunteer today, to protect our waters tomorrow.

Phone: (715) 543-2085

AIS of the Month

September: Mystery Snails

August: Eurasian Water Milfoil

July: Purple Loosestrife

June: Curly Leaf Pondweed