​Giant snails are terrorizing Florida

Last Updated Aug 5, 2015 4:44 PM EDT

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Poster from the Florida Department of Agriculture and Consumer Services warns of the invasive giant African land snail.
Florida Department of Agriculture and Consumer Services

"This is not science fiction," warns a public service announcement from the Florida Department of Agriculture. "This is real."

The video shows a giant African land snail, an invasive species with no natural predators that lives up to nine years and can grow to eight inches long. An adult can lay as many as 1,200 eggs in a year.

"We need your help," the ad implores. "See 'em, report 'em."

One of the largest and most damaging snails on Earth, giant African land snails (GALS) first invaded southern Florida in the 1960s. An eradication program that lasted nine years and cost $1 million killed 17,000 by the end of 1975.

Then, in September of 2011, a GALS was discovered in Miami.

Since the comeback, the tally in Miami-Dade and Broward Counties has grown into the hundreds of thousands.

"When the (eradication) program began, going into people's backyards, we were seeing anywhere from dozens to hundreds. It was pretty scary," Florida's Commissioner of Agriculture, Adam Putnam, told CBS News. "Because of timing, coming on the heels of real estate collapse, there were all these abandoned homes with overgrown lawns. In the tropical environment that is Miami you would really have this overgrown jungle in abandoned homes' backyards crawling with snails. To see a yard full of 2-, 3-, 4-inch snails from the roofline of the house to the trees is a sight to behold."

Puntam said it's believed the snails are being smuggled in for use in religious rites and rituals. "The santerian religion places a special emphasis on the juice of the snails," he explained.

The massive snails feed on more than 500 species of plants, including agricultural crops. They also harvest calcium from the stucco and plaster to build their shells, damaging homes. What's more, they are known to carry a parasite known as rat lungworm, which can cause a form of meningitis in humans and animals. Specimens with the disease have been identified in Miami.

"As strange or funny as it sounds, it's a threat to human health, the environment and agriculture," said Putnam.

Driven largely by reports of sightings called in by residents to a helpline, the Department of Agriculture's latest eradication program has eliminated more than 158,600 giant snails since 2011.

The effort is also helped by the keen noses of Sierra and Bear, two Black Labradors trained to sniff out GALS. Occasionally, search teams are deployed to look for the mollusks at night, when they are more active.

The snails have been found on 670 properties in from Homestead to Hollywood, Florida, but haven't been spotted elsewhere in the state.

"We are detecting fewer snails per day than we have in the past and we even have the occasional day where we're not finding any," said Putnam. "The numbers do indicate that we are wining this battle."

  • Amanda Schupak

    Amanda Schupak is the science and technology editor at CBSNews.com