Drift residues of naled and fenthion, which were applied for mosquito control, were sampled with α-cellulose pads in pineland and hammock ecosystems of the Florida Keys in 1989. These included habitats of state and federally protected insect and cactus species on wildlife refuges with no-spray zones. Naled residues were detected up to 750 m downwind in a no-spray zone in pinelands 6 h after application to adjacent target areas. Fenthion residues were detected up to 50 m downwind in hammock 15 min after application to adjacent target areas. In controlled residue degradation experiments, technical naled did not disappear significantly from pads suspended vertically from wires or laid flat on the substrate over a 240-min period. Fenthion did not disappear significantly from pads laid on the substrate but did disappear partly from pads suspended from wires. Estimated environmental concentrations of naled and fenthion in these habitats may be used to calculate ecological risk indexes for protected species.