Since 1969, Florida has battled the giant African land snail, smuggled in as exotic pets; the fist-sized invader eats 500 plant species and even the plaster off houses

It might sound like something out of a monster movie, but it’s real: a snail as big as an adult fist can chew through more than 500 varieties of plants and even scrape stucco off the side of a house. Since the 1970s, the state has had to declare the giant African land snail eradicated twice, according to the Florida Department of Agriculture and Consumer Services, and the whole saga began with three smuggled pets.

A souvenir that turned into a statewide crisis
The study titled ‘Reproductive Ecology of the Giant African Snail in South Florida: Implications for Eradication Programs,’ published in PLOS ONE, reconstructed the outbreak and found that it began in 1966, when three juvenile snails were brought back to Miami from a trip to Hawaii and kept as pets. Turns out, snails don’t stay contained. The outbreak was discovered in 1969 by the Florida Department of Agriculture and Consumer Services, and it took seven years and about a million dollars to declare the species eradicated in 1975. That would have been the end of it, except the snails reappeared in Miami-Dade County in 2011, and according to the same agency, this second eradication effort was not declared complete until 2021.

Why can one snail become thousands
Basic biology is part of what makes this species so hard to beat. Giant African land snails are hermaphrodites, meaning every snail has both male and female reproductive organs. A single mating can result in several clutches of eggs over time. The PLOS ONE study noted that the researchers measured, dissected, and counted eggs in 23,890 snails from 22 populations over two years, and found that gravid individuals ranged from 48 to 128 mm.

They also showed that the biggest treatment effect came from metaldehyde, which cut numbers most sharply, while higher humidity and warmer temperatures were linked to more snails and more egg-bearing individuals. In Florida’s climate, egg-laying occurs all year long, rather than during a single season, and about 5 percent of the population carries eggs at any given time.

A snail can lay 100 eggs at about six months old, with later clutches rising to roughly 200–1,800 eggs, according to the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service. That combo, a few founder snails plus near-constant breeding, is a big part of why three pets in 1966 could balloon into an outbreak in just a few years.

An appetite that doesn't stop at plants
The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service says fully grown adults can reach up to 8 inches in length and almost 5 inches in diameter, about the size of an average adult's fist. The snails eat more than 500 species of plants, with a particular taste for beans, peas, cucumbers, melons, and peanuts, according to the Florida Department of Agriculture and Consumer Services.

But they don’t just eat food crops. Ornamental garden plants and tree bark are also fair game, and the snails have been seen scraping plaster, stucco, and paint on buildings, most likely to obtain calcium for their shells. Not only is that a nuisance for the garden, but a real concern for the property in a state where stucco is the default look for whole neighborhoods.

The health risk hiding in plain sight
There is also a less obvious reason why officials consider this snail a public health problem rather than just a pest problem. The species can carry a parasitic nematode called Angiostrongylus cantonensis, commonly known as rat lungworm, which is a leading cause of eosinophilic meningitis in humans, according to a in the Journal of Wildlife Diseases. Researchers testing snails collected from Miami in 2013 found the parasite in 18 of 50 snails, or 36 percent, with rates of infection at individual collection sites ranging from 27 percent up to 100 percent. That’s one reason health officials advise people never to touch these snails with their bare hands.

A quarantine that's still active today
This is not ancient history. According to the Florida Department of Agriculture and Consumer Services, there are active quarantine zones in Broward, Lee, and Pasco counties. It’s illegal to move plants, soil, yard waste, debris or building materials out of those areas without a compliance agreement. Specially trained detector dogs are being used to locate snails hidden in leaf litter and mulch. It’s a reminder that an invasive species problem is never solved once and for all. It can re-emerge decades later, and the cleanup bill gets bigger each time.

The bigger lesson for pet owners everywhere
This snail’s tale is a good cautionary tale for millennials and young adults who are attracted to exotic pets, especially the kind that go viral on social media. What began as a family trip souvenir in 1966 has turned into a problem Florida is still actively managing nearly six decades later. Giant African land snails remain illegal to import or keep as pets in the United States, and wildlife officials continue to ask the public to report sightings and not try to handle them. Florida's snail saga shows just how long a single well-meaning decision can echo.