Apple snails (Pomacea paludosa Say) in Florida wetlands and lakes must contend with water level fluctuations that periodically result in dry downs.1 In recent years we have conducted field and laboratory studies to investigate the impacts of such drying events on snail populations. Our research has focused mainly on direct mortality due to desiccation. However, during one laboratory study we identified a potential threat to snail populations from the red imported fire ant, Solenopsis invicta Buren. Since their introduction to Alabama around 1940, S. invicta has expanded its range to include all of Florida.2 S. invicta in Florida prefer disturbed sites in areas with a relatively high water table.3 The highly fragmented wetland systems of Florida provide the moisture levels and disturbance profile (periodic dry downs, as well as disturbed substrata along canals and levees) favored by S. invicta. Fire ants can be found along levees adjacent to parcels of the Everglades and Upper St. Johns River marsh, on tree islands, and along the margins of central Florida lakes (Darby, pers. obs.). Fire ant colonies were reported in up to 20% of alligator nests in central Florida lakes.4 During periods of inundation S. invicta emerge from their mounds and form floating balls, thus prolonging colony survival and aiding dispersal.5 Their adaptations to seasonal flooding and their highly successful invasion of Florida may reflect the evolution of S. invicta in South American ecosystems subjected to regular flooding.6 S. invicta are predators observed killing numerous invertebrate2,6,7 and vertebrate species4,8 and have been associated with biodiversity declines in the southeastern fauna.9 The distribution of S. invicta encompasses the entire range of the Florida apple snail. Given the critical position of the apple snail in the food web of Central and South Florida wetlands,10 vulnerability to S. invicta is of concern. We observed S. invicta attacking apple snails while conducting experiments on snail survival during dry down conditions. Ten tanks (120 cm 3 61 cm 3 46 cm), each with a sand substratum, were set up in a grassy area outside the Florida Caribbean Science Center (USGS-Biological Research Division, Gainesville, FL) in June 1998. S. invicta mounds were present in the grassy area around the tanks. These were treated throughout the experiment with a granular bait formulation of the insecticide hydramethylnon (AMDRO®). [S. invicta identification was verified at the USDA Red Imported Fire Ant Laboratory, Gainesville, FL]. Each tank contained 18–20 adult apple snails with mean (6SD) shell widths of 33.5 mm (63.5 mm). Four tanks were used as controls and kept filled with water, while the other six were Moll. Stud. (1999), 65, 507–510 © The Malacological Society of London 1999