While invasive apple snails have not yet been observed in Corkscrew Swamp Sanctuary, scientists and land managers know that unfortunately, it’s only a matter of time.

Our native ‘Florida apple snails’ are a common sight in wetlands, along canal banks and in ponds and other permanent water bodies. They are a preferred food source for many animals, including Everglade snail kites (an endangered raptor native to Florida and Cuba), limpkins, turtles and otters. While these snails are well camouflaged to avoid predation, empty shells can often be found in piles along the edges of wetlands. Often more obvious than the adult apple snails, white clusters of Florida apple snail eggs can commonly be seen above the surface of the water on cypress trees, plants and canal banks.

In the last decade or so, three species of invasive apple snails (native to South America) have become established in South Florida and scientists fear they may pose a threat to our native ecosystem. While the shells of adult snails are very difficult to tell apart, apple snails can easily be identified by differences in the egg masses that they lay.

Island apple snails are the most widespread invader in the Southeast U.S., currently established in coastal states from South Carolina to Florida to Texas. At full size, adults are noticeably larger than our native apple snail, but younger individuals cannot be easily distinguished. Island apple snail egg masses are bright pink and the individual eggs are smaller than those of our native (native apple snail eggs are also pink when they are first laid, and they turn white as their outer shell dries).

Spike-topped apple snails are established throughout South Florida and have been collected in several places farther north on the Florida peninsula. Egg masses are salmon-colored.

Titan apple snails are currently established only in Palm Beach County and their egg masses are a seafoam/pastel green color.

While these non-native apple snails rapidly spread throughout our region, scientists are working hard to better understand their potential impacts. Early observations suggest they are displacing native apple snails, perhaps by consuming young native snails.

The effects of these invasions on apple snail predators are unknown. While we currently have no known control methods for adult snails, egg masses can easily be destroyed by crushing or drowning them. Caution should be taken, however, to ensure eggs are from non-native snails before destroying them. Information on identifying apple snails and reporting non-natives you encounter can be found online using FWC’s Nonnative Apple Snail Reporting page.

Article by Dr. Shawn Liston.