SUMMARYThe anal papillae of freshwater mosquito larvae are important sites of NaCl uptake, thereby acting to offset the dilution of the hemolymph by the dilute habitat. The ion-transport mechanisms in the anal papillae are not well understood. In this study, the scanning ion-selective electrode technique (SIET) was utilized to measure ion fluxes at the anal papillae, and pharmacological inhibitors of ion transport were utilized to identify ion-transport mechanisms. Na + uptake by the anal papillae was inhibited by bafilomycin and phenamil but not by HMA. Cl -uptake was inhibited by methazolamide, SITS and DIDS but not by bafilomycin. H