‘They’ll kill the pond’: What to know as apple snails infest Horry County again

Sometimes this summer, as Bernard Husson has mowed the grass between his white picket fence and the stormwater pond in his neighborhood, he’s noticed something strange: Bubblegum-pink sacks of eggs clinging to the reeds and aquatic plants springing out of the water, with large, spiral shells littered along the water’s edge.

Nate Victoria, who lives across the pond from Husson in Seawind Estates, has noticed them, too.

“I’ve been seeing them since 2020,” Victoria, a high school sophomore at Socastee High School, said. “They lay these big ‘ole pink eggs on the plants. They’ve got this pretty cool black goo on their face.”

What Husson and Victoria have been seeing are apple snails, a rather large species of the shelled gastropods, that have sprung up around Horry County ponds and creeks in recent years. The problem? Apple snails are invasive in the United States, and can cause issues for local ecosystems. The snails breed rapidly, are difficult to kill and can consume the algaes and other substances that fish and turtles need to survive. In extreme scenarios, the snails can overrun ponds or creeks, starving out other creatures that live there.

Apple snails can also carry diseases, like rat lungworm, which can cause meningitis in the brain and spine, though no cases of the snails transmitting that disease to humans have occurred in the United States to date.

“They’re strange little buggers,” said Chris Page, the aquatic nuisance program manager for South Carolina’s Department of Natural Resources.

Page said that in areas that rice is grown, the snails can cause major problems as they’ll breed rapidly and eat the rice plants, potentially ruining crops for farmers. In Horry County, the snails are more of a fascination or annoyance and less of an immediate threat. Still, leaders of homeowner associations and state officials are beginning to study ways to rid the snails from the area.

“They’re going to cause more harm in that going to proliferate,” Page said. “I don’t think its possible to eradicate them.”

Apple snails’ origin

If the spiral on an apple snail’s shell looks familiar, it’s because you may have seen them in pet stores before. The snails have been sold as pets in the Grand Strand in the past, and, as best as Page and other officials can determine, someone freeing their pet snails into a nearby creek may have been the start of them proliferating in Horry County. That, plus an unmaintained retention pond, fueled the spread of the spiral-shelled mollusks.

“We think it started at a mobile home park where they weren’t maintaining their retention pond,” Page said. “We found terrarium remnants. (There are) only two areas in South Carolina that have them (and) the Socastee area was ground zero.”

That’s what Cam Crawford, the County Council member for Socastee, heard, too.

“That’s what I heard, that a few years back somebody had a bunch of them in an aquarium and dumped them into a creek and they migrated from there,” Crawford said. “Last summer it was strange, there were all these little snails, they were the size of maybe half a dime.”

Crawford said he’d frequently step on them and hear a crunch when he walked near his home.

The formal name for apple snails is ampullariidae, and the species is classified as a family of large, freshwater snails with gills and special appendages that cover the gills. The snails also have a lung, meaning they can breath both underwater and on land. Male and female snails are needed to breed, though the snails can change sex to keep breeding happening, Page said. The snails are native to the South and Central Americas, and thrive in tropical areas.

When the snails breed, they lay dozens, if not hundreds, of eggs at a time, enclosed in bright pink sacks that have the appearance of chewed-up bubblegum. When the snails live in ponds, they’ll climb up a reed or the stock of another aquatic plant and lay the eggs, before returning home. The snails also have the ability to bury in mud to hide.

The snails have few natural predators, but fish like shell-crackers and blue catfish can eat them, as can raccoons and otters. However, Page noted, if the snails are allowed to live until they grow large — the snails can reach up to 5 inches across — those predators can’t, or won’t, try to eat the snails. Blue catfish are the one exception, willing to eat the snails no matter how large they grow.

“The easiest thing to do is to tell people when they see the egg sacks… is to knock them into the water. They’ll die,” he said. “Just anytime you see those eggs, push them back in the water.”

Page said low concentrations of copper can also kill off the snails, though that treatment is tricky because the snails can detect the copper if the concentration is too high. In that case, the snails will sense the copper and bury themselves in the mud until the copper concentration has gone down. But certain low levels of copper in water can evade the snails’ detection and eventually kill them, Page said. Blue catfish, Page said, are typically a safe bet for getting rid of the creatures.

“If I had a pond I’d put some blue catfish in it and copper,” he said.

Where are the snails?

In Bruce Bunker’s Socastee neighborhood, the stormwater ponds have become infested with apple snails, alarming him and other neighbors. Bunker, the president of the Lake Park Plantation neighborhood’s homeowner’s association, has sent out notices to residents advising them to kill any apple snails they come across, and advising them that they’re an invasive species. He’s contacted local officials, and Page or other DNR officers plan to visit the neighborhood’s ponds in coming weeks to investigate the problem.

In an advisory sent to residents, Bunker warned that ducks or other animals could be harmed if they eat the snails, though Page said there’s probably little risk to people’s dogs or pets.

Bunker said he and his HOA are trying to get a management company to help trim foliage around the ponds so the snails have fewer places to lay eggs, and are looking into adding shell-cracker fish in coming weeks. In the meantime, he and the other residents have been up to their own devices.

“The only way we’re dealing with it right now is people are scraping the pink egg sacks into the water, apparently that kills them,” he said. “A lot of the residents are busy scraping them into the water and crushing them.”

In the Palmetto Glen neighborhood, Lynn Bear said the apple snails have appeared in their ponds, too.

“We have apple snails in our stormwater ponds and they’re a bugger,” she said. “They clean out the ponds which might seem like a good thing, but...the fish won’t have anything to eat, the turtles won’t have anything to eat.”

Bear, too, said she and her neighbors are working to scrape eggs into the water and rid the area of the pesky mollusks.

“Scrape them off, get them in the water,” she said. “They’ll actually kill the pond if you let them.”