Giant African Snail, Achatina fulica (Bowdich)

Scientists consider the giant African snail to be one of the most damaging land snails in the world. Luckily, it has not established a foothold in the continental United States, even though that almost happened at least twice. Originally from an area south of the Sahara in East Africa, this snail has established itself in Asia and the Indo-Pacific Islands, including Hawaii. The two near misses took place in California just after World War II and in Miami, FL, in 1966.

In the Florida incident, a young boy returning from Hawaii smuggled three giant African snails into Miami as pets. His grandmother eventually released the snails into her garden. Seven years later, more than 18,000 snails had been found along with lots of eggs. It took the State of Florida almost 10 years and cost more than $1 million to rid itself of this slow but persistent pest.

Compared to our native snails, this foreign pest is really big—about 8 inches (200 mm) long overall with the shell making up half its length. It is also showy, with a light-brown shell striped with brown and cream bands.

Two qualities make this tropical snail especially dangerous here. First, it can survive cold conditions and even snow by aestivating. This means that the snail will become slow and sluggish, essentially hibernating until warm weather returns. Theoretically, it could live in most of the United States.

Second, the giant African snail is a whiz at reproduction. For one thing, each snail contains both female and male reproductive organs! After a single mating session, each snail can produce a batch of 100 to 400 eggs. And it can keep this up several more times without having to mate again. In a typical year, every mated adult lays about 1,200 eggs. Giant African snails can live as long as 9 years, and that is plenty of time to cause trouble in the local environment.

One of the threats posed by the giant African snail is not what it eats, but what it carries. This pest can be a vector for human diseases such as eosinophilic meningitis. This disease is passed along by rat lungworm parasites that can be found on the snail. If the snail is eaten raw or isn't completely cooked, diners eating giant African snails might get the rat lungworm parasite as a side dish without knowing it—and meningitis for dessert.

Another threat is the voracious snail's appetite. It is known to eat at least 500 different types of plants, including breadfruit, cassava, cocoa, papaya, peanut, rubber, and most varieties of beans, peas, cucumbers, and melons. Unlike people, giant African snails are never picky eaters. If vegetables or fruits are not available, the snails will munch on a wide variety of ornamental plants and even tree bark. All the world's a buffet table to this snail.