The Invasive Giant African Land Snail Has Been Spotted in Florida

An invasive species of large snail that can grow as large as a human fist and carries a parasite that can cause meningitis has been spotted in Florida’s second-most-populous county, prompting officials to set up a quarantine zone to try to contain it.

The species, the giant African land snail, was detected earlier this month in Miramar, Fla., north of Miami. On Tuesday, after completing a survey of the area, state agriculture officials decided to place a 3.5-square-mile section of Broward County under quarantine.

People who live within that zone may come and go, but it is illegal to move the snails as well as any soil, debris, yard waste or plants within or out of the quarantine area without a compliance agreement from the Florida Department of Agriculture and Consumer Services.

African land snails thrive in warm, wet climates, underscoring the urgency of ramping up mitigation efforts, said William Kern, an associate professor at the University of Florida who specializes in nuisance wildlife management.

“This is when we want to knock them down because this is when they are really going to be cranking up their population,” Dr. Kern said.

The giant African land snail is “one of the most invasive pests on the planet,” according to the Florida agriculture department. The snails feed on at least 500 types of plants, including crops like sweet corn, beans, lettuce and cabbage. They can have a devastating effect on Florida’s agriculture and natural areas “as they cause extensive damage to tropical and subtropical environments,” the department said in a statement announcing the quarantine.

The snail also carries a parasite, rat lungworm, that causes meningitis in humans and animals. People can become infected if they come into contact with the snail or its slime — for instance by eating unwashed vegetables or produce that one of the snails has touched.

Florida agriculture officials are using a snail bait that contains metaldehyde, a pesticide approved for residential use, to kill the snails.

The giant African land snail has been eradicated twice in Florida since the species was first detected in the state in 1969, according to the Florida agriculture department: first in 1975 and again in 2021, after the snails were detected in Miami-Dade and Broward Counties in 2011.

Last year, however, they were spotted in Pasco County, north of Tampa, prompting a quarantine that remains active. Lee County was put under quarantine this year.

The agriculture department did not immediately provide a timeline for how long it would take to eradicate the snails this time.

It’s unclear exactly how the snails made their way back to Florida. It’s possible they came over as stowaways on shipping containers, or as eggs in potted plants that people brought home from the Caribbean, Dr. Kern said. Some may have also survived previous mitigation attempts, he said.