National Geographic Daily News
Giant African land snails are held during a press conference.

A person holds giant African land snails in Miami, Florida, on September 15.

Photograph by Joe Raedle, Getty Images

Ker Than

for National Geographic News

Published April 17, 2013

A new outbreak of giant, disease-carrying snails is threatening Florida's crops, experts say.

The giant African land snail is finding itself right at home in the Sunshine State, whose hot and humid climate resembles the species' tropical Nigerian habitat. (Related: "Giant Snails, Once a Delicacy, Overrun Brazil.")

Now found throughout the world, including the contiguous United States and Hawaii, these invasive plant-eaters pose a particular danger in Florida because of its vibrant agricultural industry.

"We're producing food that the nation depends on ... [and this snail] eats 500 different plants, including pretty much everything that grows in Florida," said Mark Fagan, a spokesperson for the Florida Department of Agriculture.

"This is not something we can walk away from. These snails are a major threat to Florida's agriculture."

Some snails are smuggled into the U.S. as pets or for religious practices and, once here, get transported around the country in plants or cargo by unwitting people, experts say. (Read more about invasive species.)

"These snails have been intercepted by customs and border patrols at airports. There was one woman who was flying back from Nigeria [who] was intercepted, and she had hidden some snails under her skirt," Fagan said.

The exact reasons for smuggling the snails is unknown, he added, "but we are aware that these snails are used in certain religious practices. Some people also like to keep these snails as pets because they're exotic."

Hardy Pest

There have been outbreaks of the snails in Florida and other parts of the country before, but Florida's latest boom began a year and a half ago in Miami-Dade County.

"They're very prolific," said Awinash Bhatkar, a snail expert with the Texas Department of Agriculture.

After reaching adulthood at about six months of age, the snails can produce up to a hundred eggs per month and live more than eight years.

Whereas most snails feed on decaying organic material or on leaf molds, the giant African land snail is one of the few snails that actually feed on plant parts themselves, Bhatkar said.

In addition to plants, young snails are known to munch on house stucco and even cement as they seek out calcium to strengthen their growing shells.

The snails also pose a human and animal health threat because they can eat rat feces and contract rat lungworm, which can cause a rare form of meningitis.  (See pictures of infectious animals.)

"The parasitic nematode that causes rat lungworm can be present in the slime of the snail," Fagan explained. "So if a person comes in contact with the snail, the nematode present can then enter the person's body, eventually making its way into the brain."

He added, "We have confirmation from the [U.S. Centers for Disease Control and Prevention] that rat lungworm disease is present in some snail samples that we sent up to them."

Because of this risk, the Department of Agriculture's Fagan said anyone who thinks they have a giant African land snail infestation should call the department immediately at 888-397-1517, rather than try to kill the snails themselves.

"We'd rather go out and tell you, 'Nope, that's not a giant African land snail,' than you not call us ... We don't want to endanger anyone's health. We have protective gear, and we know how to pick them up."

Long Battle Ahead

Fagan is confident that his department has the outbreak in Miami-Dade County under control since switching to a much more aggressive form of bait that's more lethal to the giant African land snail.

The bait contains a bittering agent that makes it unpalatable to domestic animals and wildlife.

"It's truly a challenge, but it's not a challenge that we can't overcome," he said. "We feel very confident that we will be able to reach eradication."

If past experience is any guide, however, achieving that goal in Miami-Dade County could take years. (Read about Burmese pythons thriving in Florida.)

In 1966, an outbreak occurred in North Miami after snails smuggled by a 10-year-old boy from Hawaii were released by his grandmother. Nine years, and about 18,000 dead snails later, the snail pest was finally removed.

But the Miami-Dade outbreak is much bigger, and as a result could take much longer to contain.

"We've collected 120,000 snails in just the past 18 months," Fagan said.

5 comments
Ella Taylor
Ella Taylor

feed it to something. find out what would eat it naturally

Brian Rucci
Brian Rucci

The problem with using a natural predator is that the predator will not only eat the snails. So releasing a new spieces to kill this one just hurts the ecosystem more. The only time a natural predator is an option for removing a non-native pest is when a native predator begins feeding on them.

Christine Dell'Amore
Christine Dell'Amore

@Barbara Wunder Thanks for your question! According to the scientist, all food crops grown in Florida could be affected. So some examples are oranges, grapefruit, tomatoes, bananas, strawberries, watermelons, cabbage, snap beans, and bell peppers.

c n
c n

@Christine Dell'Amore @Barbara Wunder How do you know what type of snail you have? I jog past a drainage ditch, in Brandon, FL(East Tampa), and I see hundreds of snails about the size of a 7 year-old's fist. From a distance, they do not appear to to have a "pointed" shell.

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