The three Corethrella spp. endemic to the southeastern United States are thought to feed on the blood of frogs (Hylidae: Anura) and are attracted to the call of male tree frogs. This project investigates the attraction of corethrellids to the calls of native frogs. Data will be presented on host call preference determined by using traps baited with recordings of frog calls. Response to these frog calls will be analyzed in relation to abundance and calling behavior of frog species in situ. Analysis of blood meals will be performed to determine if flies feed on the same frog species whose calls are most attractive.