ST. GEORGE — With the recent rains, locals have reported being overrun with snails in areas across Southern Utah, and biologists say they could be invasive.
According to Dr. Frederic Govedich, a biology professor at Southern Utah University, snails often appear following or during rainstorms to find a mate and lay eggs. They can be found in small puddles, grass and other moist areas.
“And then they’ll hatch, and everyone’s like, ‘Oh, that’s a snailfest,'” he said.
While some snails are native to Southern Utah, many species are extremely small, Govedich said. The snails appearing in Southern Utah lawns are most likely introduced or invasive species, but it’s difficult to know without examining a specimen or a clear photo.
Native snails are less commonly seen and often isolated to springs, streams and ponds, where they evolved over millennia, said Dr. Samual Wells, an assistant professor in SUU’s biology department.
“They’re usually in a spring system, and they’re associated with that spring,” Govedich added. “And then you just go like 10 feet away from a spring, and they’re gone. So they’re only in that one spot. We can even go to another spring that’s like two miles away — it’s a different species.”
Wells added: “Now what we’ve done is we’ve dumped a bunch of water all over the place for our lawns and our golf courses, et cetera, and that’s what we’ve created — habitat suitable for some species of snails. And what’s occupying those are not natives. That’s the invasive ones.”
The large, brown snails often seen in gardens could be brown garden snails native to the Mediterranean and Western Europe and introduced locally, according to a Utah Division of Wildlife Resources article by biologist Kate Holcomb.
Brown garden snails were first introduced to California in the 1850s and have since been spread across the U.S. by humans transporting plants, using them as a food source or by snail hobbyists, she writes.
They prefer dark, damp places and dense vegetation, like that found in gardens, and eat both living and dead vegetation, Holcomb added.
Brown garden snails are most active from April to October and mate multiple times through the season, Holcomb writes. Because they are hermaphroditic and have both male and female reproductive organs, each snail could produce several hundred eggs.
When conditions aren’t favorable, they burrow into the soil or a crevice and become dormant, sealing off the opening of their shells with a layer of mucous. This process is “similar to using plastic wrap to prevent food from drying out in the refrigerator,” she states.
One St. George resident posted on Facebook about a large number of small, pink snails in her yard that Govedich said could have originated from Asia or South America, spreading out after someone dumped their aquarium snails.
Snails and their shellless relatives, slugs, feast on various plants and can cause damage to seedlings and maturing fruits and vegetables that grow close to the ground.
The mollusks chew irregular holes in leaves, eat flowers and clip off small plants and parts of vegetation. They are known to damage strawberries, tomatoes, basil, lettuce and other garden regulars, according to the Utah State University Extension.
“They love certain ornamentals and are very destructive on hostas, daylilies, dahlias, delphiniums and marigolds,” the university states. “Because other pests can cause damage that resembles their feeding, look for the silvery mucous trails. That confirms that it is slug or snail damage and not earwigs, caterpillars or other chewing insects.”
No such thing as ‘away’
Govedich said there is no such thing as “away” when it comes to invasive species and that animals that are flushed, dumped down storm drains or abandoned outdoors often find a way to survive.
For instance, they’ve found nonnative leeches and goldfish thriving in desert ponds and sewer systems. Should invasive snails invade local spring systems, they can potentially drive endemic species to extinction.
“People buy these things, get tired of them and let them go, and we just can’t do that because things like this happen,” he said. “There are big issues around Salt Lake for the same thing — I mean invasive species. And then once they’re there, they’re really, really hard to get rid of because they can hide in little niches and cracks and stuff like that, and wait for the next rainy season.”
The species’ natural predators and parasites are also absent from Southern Utah, giving them a “free ride,” Wells said, as many native bird species aren’t evolved to eat them.
While many introduced snail species will dehydrate and die in St. George’s hot and dry climate, some may find a way to survive and need to be killed, said Dr. Bonnie Bain, a biology research associate at SUU and adjunct professor at Utah Tech University.
One way to prevent their spread is to avoid creating suitable habitat. Because snails require continuous moisture, locals can install drip lines to target specific plants and reduce the water in the yard, Wells said.
Replacing grass with drought-resistant landscaping and cleaning up puddles and wet spots will make it more difficult for snails to reproduce, Govedich added.
Several Facebook commenters suggested using beer to kill nonnative snails, which does work, said Dr. Bill Heyborne, biology professor and dean of Walter Maxwell Gibson College of Science at SUU. The mollusks are attracted to the smell and either drown or die of alcohol poisoning after falling or crawling into the container.
Other methods of controlling snails include creating barriers with copper mesh or diatomaceous earth and handpicking snails out of the garden and either squishing them or dropping them into a container of soapy water, Holcomb writes.
While they may appear to be “just taking over everything,” Wells said there are more endangered or extinct mollusks in North America than any other group of invertebrates.
To support native snail species, Southern Utans should be careful around delicate desert spring systems, which are often the foundation of ecosystems, Govedich said. If people pick up rocks, they should put them back where they were found, as not doing so could kill the organisms living on them.
However, Bain said it’s best to “leave the rocks alone.”
Sometimes, individuals cover springs using boxes or other items to protect them, but this can be counterintuitive and harm the system, Wells said, adding that fencing is a more appropriate solution.
There are approximately 57 species of land snails in Utah, Holcomb writes. Western glass snails, Vitrina pellucida, are common throughout Utah, often found in decaying leaves or under logs in the forest, Holcomb states.
They have flexible shells that are too small for them to retract fully. They consume calcium from plants, which is passed along to other animals, like birds, cycling the mineral through the environment.
“And most people say, ‘Well, who cares?’ But it’s like, well, you know, these are unique systems, and they’re unique species, and they have their role in those systems,” Govedich said.
Suppose a person finds a snail and is unsure whether it is native or introduced. In that case, they can email a clear photo to Bain or Govedich or ask how to send them a specimen. Doing so could benefit an SUU student studying native mollusks. Alternatively, they can contact their local Utah DWR field office.
Additionally, Utah State University provides a guide for controlling snails and slugs here.
Photo Gallery
Pink snails crawl across a lawn in St. George, Utah, Aug., 2023 | Reader submitted photo, St. George News Pink snails crawl across a lawn in St. George, Utah, Aug., 2023 | Reader submitted photo, St. George News A snail navigates shallow pools at Quichipa Recreation Area, Cedar City, Utah, Sept. 2, 2023 | Photo by Alysha Lundgren, St. George News A snail navigates shallow pools at Quichipa Recreation Area, Cedar City, Utah, Sept. 2, 2023 | Photo by Alysha Lundgren, St. George News Snails navigate shallow pools at Quichipa Recreation Area, Cedar City, Utah, Sept. 2, 2023 | Photo by Alysha Lundgren, St. George News Snails navigate shallow pools at Quichipa Recreation Area, Cedar City, Utah, Sept. 2, 2023 | Photo by Alysha Lundgren, St. George News A snail shell sits nestled among debris on the forest floor, Dixie National Forest, Utah, date unspecified | Photo by Alysha Lundgren, St. George News A snail moves across a leaf, date and location unspecified | Photo by Alysha Lundgren, St. George News Garden snails sit in the snow, date and location not specified | Photo courtesy of the Utah Division of Wildlife Resources, St. George News A person holds a Western glass snail, date and location not specified | Photo courtesy of the Utah Division of Wildlife Resources, St. George News A spring snail close up, date and location not specified | Photo courtesy of the Utah Division of Wildlife Resources, St. George News Spring snails spend time in clear water, date and location not specified | Photo courtesy of the Utah Division of Wildlife Resources, St. George News A Vallonia snail's size is compared to a dime, date and location not specified | Photo courtesy of the Utah Division of Wildlife Resources, St. George News A mountainsnail feeds after a rain storm, date and location not specified | Photo courtesy of the Utah Division of Wildlife Resources, St. George News Mitered vertigo snails are compared to a dime, date and location not specified | Photo courtesy of the Utah Division of Wildlife Resources, St. George News
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