Giant African land snails are one of the most destructive invasive species to repeatedly establish themselves in Florida. These snails, native to East Africa, can grow shells up to 8 inches long, eat more than 500 types of plants, and carry a parasite capable of causing meningitis in humans. Florida has fought multiple infestations since the 1960s, each requiring years of intensive effort and millions of dollars to contain.
How They Got to Florida
The first known Florida infestation traces back to 1966, when a child returning from a trip to Hawaii smuggled three giant African land snails into Miami. His grandmother eventually released them into her garden. Within seven years, more than 18,000 snails had been found in the area, along with large numbers of eggs. The state ultimately eradicated that population, but it took a full decade and cost $1 million, a significant sum at the time.
The snails returned in September 2011, again in Miami-Dade County. The USDA and the Florida Department of Agriculture and Consumer Services launched another eradication program that collected more than 168,000 snails over the following years. That effort was declared successful in 2021. Then in June 2022, the snails were detected again, this time in Pasco County north of Tampa, and additional populations were later confirmed in Broward County. Florida issued quarantine orders for affected areas, restricting the movement of plants, soil, and yard debris that could harbor snails or eggs.
How to Identify Them
Giant African land snails are hard to mistake for native species once you know what to look for. Adults have a cone-shaped shell that typically reaches 4 to 6 inches in length but can grow up to 8 inches, making them one of the largest land snails in the world. The shell has a distinctive brown coloring with darker brown or tan vertical stripes. Their soft body is a grayish-brown.
Florida does have native snails and some other non-native species, but none come close to the size of a full-grown giant African land snail. Juvenile snails can be trickier to identify since they’re smaller and could be confused with other species. If you find a snail in a quarantine area that you suspect is a giant African land snail, the state asks that you avoid handling it with bare hands and report it to the Florida Department of Agriculture.
Why They Spread So Quickly
These snails are prolific breeders. Each one is a hermaphrodite, meaning every individual can produce eggs. A single snail can lay around 1,200 eggs per year in multiple clutches, with eggs hatching in as little as 11 days under warm, humid conditions. South Florida’s subtropical climate is nearly ideal for them, providing year-round warmth and moisture.
They’re also not picky eaters. Giant African land snails feed on more than 500 plant species, including fruits, vegetables, ornamental plants, and tree bark. When plant material is scarce, they eat stucco, plaster, and other calcium-rich building materials to get the calcium they need for shell growth. That habit means they can damage not just crops and gardens but the exterior walls of homes and buildings.
Health Risks to Humans
The most serious human health concern is rat lungworm, a parasitic roundworm that giant African land snails can carry. Snails pick up the parasite’s larvae from rat feces, and humans can become infected by handling snails, eating undercooked snail meat, or consuming raw produce that a snail has crawled across, leaving behind contaminated slime.
Most people who ingest rat lungworm larvae never develop symptoms. The parasite typically dies on its own in humans without completing its life cycle. In some cases, however, the larvae migrate to the brain and cause eosinophilic meningitis, an inflammation of the membranes surrounding the brain. Symptoms include severe headache, neck stiffness so intense you can’t touch your chin to your chest, nausea, vomiting, tingling sensations, vision changes, confusion, and sensitivity to light. The condition is treatable but can be serious, particularly in young children or people with weakened immune systems.
You don’t need to eat a snail to be at risk. Simply handling one with bare hands and then touching your face, or eating garden vegetables that haven’t been thoroughly washed, can be enough if the snail was carrying the parasite.
Damage to Agriculture and Property
Florida’s agricultural industry is particularly vulnerable. The snails devour citrus, papaya, beans, lettuce, and dozens of other crops grown commercially across the state. Their appetite is broad enough that virtually any garden or farm in an infested area is at risk. Because they feed primarily at night and shelter in hidden, moist spots during the day, an infestation can grow significantly before anyone notices.
The structural damage is unusual for a pest. Giant African land snails actively consume stucco and plaster from building exteriors to obtain calcium. In heavily infested neighborhoods, residents have reported visible scoring and pitting on their walls. They also leave large amounts of feces on surfaces they travel across, creating sanitation problems on patios, walkways, and the sides of buildings.
What Florida Is Doing About It
Florida treats every detection of giant African land snails as an emergency. When a new population is confirmed, the state establishes a quarantine zone, typically covering the area within a certain radius of confirmed sightings. Within that zone, it’s illegal to move soil, plants, yard waste, or building materials without inspection, since snails and their eggs can hitchhike in any of these.
Eradication teams apply a snail-specific bait containing a pesticide approved for use around homes and gardens. Workers also conduct surveys by searching yards, vacant lots, and agricultural land on hands and knees, collecting snails by hand. The process is labor-intensive and slow. The first Miami eradication took 10 years. The 2011 effort took roughly a decade as well before the population was declared eliminated. The more recent detections in Pasco and Broward counties have triggered similar multi-year campaigns.
If you live in or near a quarantine zone, the most practical steps are to check your yard regularly (especially after rain), avoid moving soil or plants out of the area, wash all garden produce thoroughly, and never handle the snails without gloves. Reporting sightings quickly is one of the most effective things residents can do, since catching a new cluster early dramatically improves the chances of successful eradication.