Gardener's Nightmare: Giant snails

Learn about a foreign garden pest that has caused past problems in the U.S., and could cause more if we're not careful.

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By Dan Vierrial, Sacramento Bee

Snail problems, eh? Be thankful giant African land snails aren't sliming your garden.

Several of these voracious snails, which can weigh as much as 20 pounds and stretch 15 inches, recently were confiscated from a classroom in Wisconsin. Although the snails are illegal to possess in this country, the school had been using them as teaching aids. Giant African land snails also have been seized in three other Wisconsin cities.

The giant snails are known to gobble up at least 500 different plants, including most vegetables, ornamentals, melons and sunflowers. They rapidly reproduce in warmer climates. The giant snail is also believed to pass along eosinophilic meningitis through its on-board entourage of parasites.

According to the U.S. Department of Agriculture, a boy smuggled three giant snails into Miami during the 1960s. His action ultimately led to an expensive, 10-year eradication program. His grandmother let them loose in the yard, and eventually more than 18,000 giant snails were discovered and destroyed.

Giant snails can be baited, but the odor of large, decaying mollusks reportedly can be nauseating. These aren't little brown garden snails.

Slipping undetected into countries is always a possibility, as the snails are great hitchhikers on cargo.

"Nobody is likely to miss the adults, but their eggs really move around a lot," says Lynn Kimsey, professor of entomology at the University of California, Davis. "For instance, like on nursery plants."

Others have been discovered in ports and airports. A few years ago, a live giant snail was discovered in a suitcase at Perth International Airport in Australia. A woman had picked up a shell on a Malaysian beach and packed it without realizing a snail was still inside.

Kimsey says U.S. Customs has become lax about checking for plant pests, which could open the door wider for the introduction of new plant and animal diseases and pests.

"When you come through customs into the U.S., they don't check for anything anymore unless it's explosives, guns or profiling," she says after two recent trips to Peru and Nicaragua. "We were bringing in live plant material with permits and other things they used to get fairly worked up about. I could have had one of those giant snails sitting on my shoulder and they wouldn't have cared. It's pretty scary."

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