Description: There are two genetic types of New Zealand mudsnails: Clone 1 and Clone 2. Clone 1 was first discovered in Idaho in the 1980s, and has most recently been discovered in a southern Wisconsin stream. Clone 2 is in parts of the Great Lakes Region: Lake Erie near Cleveland, Lake Michigan near the Waukegan Harbor, and Lake Superior near the Duluth-Superior Harbor.
Identification: Very small. It is an average of 1/8 of an inch long with 7-8 whorls with a right-handed coiling and deep grooves. Shell color varies from gray and dark brown to light brown.
Habitat: Native to New Zealand. Found in flowing freshwater with silt/sand sediment to very brackish rivers; lives in water as deep as 60 feet in freshwater lakes or reservoirs.
Reproduction: Self reproducing females make up 95% of their population and give birth to well-developed clones. Females can produce 20-120 embryos per female and produce an average of 230 juveniles per year.
Impact and Damage: May affect critical food webs in trout streams and other waters. They also may compete for food with native bottom-dwellers. Lakes predators and reproduces at an alarmingly high rate. Colonizes quickly; can reach densities of 500,000 individuals per square meter.
Similar species: Difficult to distinguish from native snails, but shell more elongate.
Monitoring and rapid response: Clean recreational equipment is crucial in preventing their spread. Chemical treatment using Bayer 73 copper sulfate, and 4-nitro-3trifluoromethylphenol sodium salt may be used in small lakes and ponds that are isolated from drainages.
Credits: The information provided in this factsheet was gathered from the Global Invasive Species Database and the Michigan Department of Environmental Quality.
Individual species images that appear with a number in a black box are courtesy of the Bugwood.org network (http://www.invasive.org).Individual photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (http://images.google.com).