Giant African Land Snails Invade South Florida Again

By: Sarah Gleim  | 

Giant African land snails
Giant African land snails like these have been spotted again in South Florida. The invasive mollusks are bad news. Roberta Zimmerman, USDA APHIS, Bugwood.org

They say everything is bigger in Texas, but that may not hold true when it comes to snails. And that's not necessarily a good thing. That's because Florida has seen an invasion once again of the notorious giant African land snail (Lissachatina fulica).

The Florida Department of Agriculture and Consumer Services (FDACS) confirmed the presence of the giant African land snails (GALS), June 23, 2022, in Pasco County after a master gardener first reported seeing one. Six days later, FDACS quarantined the area to try to contain and treat for the invasive snails. A FDACS public information director told CNN the snails in Pasco County likely originated from the illegal pet trade.

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Why Are Giant African Land Snails So Bad?

So why are these snails such a problem? FDACS says they're one of the most invasive pests on the planet. They eat at least 500 different types of plants, so they're potentially devastating to Florida agriculture and natural areas. They can cause extensive damage to tropical and subtropical environments, according to FDACS.

But they're also harmful to humans. They can carry a parasite known as rat lungworm that is known to cause meningitis. Humans can get infected with rat lungworm if they eat raw or undercooked snails infected with the parasite. People also can get sick after eating contaminated produce, such as lettuce.

The Centers for Disease Control and Prevention (CDC) says it doesn't know if the giant African land snails in the United States are infected with rat lungworm, but warns people should not handle the snails without wearing gloves. It also advises people thoroughly wash fresh produce to prevent infection. The snails are illegal to own, import or sell in Florida without a permit for these reasons.

And that name? They're not known as giant snails for nothing. These massive mollusks dwarf all others — in Florida and anywhere else on Earth. Their shells are usually light to dark brown with vertical stripes, and they can grow up to 8 inches (20 centimeters) long. Compare that to other typical Florida snails, which average between 1 and 1.5 inches (2.5 and 3.8 centimeters) in length.

Giant African land snail
There's a reason these massive mollusks are called giant snails. Look at the size of that thing!
Brian Little, The University of Georgia, Bugwood.org

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Geographic Distribution and Lifespan

Experts believe the giant African land snail is originally from East Africa, though it is now found in the Ivory Coast and Morocco, and throughout the IndoPacific Basin, the Caribbean, Brazil and northernmost Argentina. It was first detected in Havana, Cuba, in 2014 and has rapidly spread across the island ever since. A population was discovered in Costa Rica in 2021, as well.

These snails can survive in many environments, though they do require calcium. They thrive in locations rich with limestone, marl, and even concrete and cement. They live on average between three and five years, but can live as long as nine years.

In that time, they reproduce fast. Adult snails have both male and female sexual organs, but they still need to mate to produce eggs. Once they do, one snail can lay eggs for up to 380 days and produce between 400 and 1,000 eggs in one year. The snails bury the eggs in cool soil and when they hatch, juvenile snails eat their eggshells and then burrow underground for up to two weeks.

If conditions get bad for adult snails, they can bury themselves in soil and stay dormant for up to a year.

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Eradicating Them Florida

This isn't the first time Florida has seen an influx of giant African land snails. The pests were first detected in 1969 and eradicated in 1975. The most recent eradication took 11 years — from 2011 to 2021 — during which FDACS worked with the U.S. Department of Agriculture (USDA) and K-9 detector dogs to find and remove 168,538 snails from 32 areas in Broward and Miami-Dade counties. Now the work begins in Pasco County.

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