A survey to identify natural potential vectors of canine heartworm in the enzootic area of Vero Beach, Florida, revealed three species of wild-caught mosquitoes harboring presumed Dirofilaria immitis larvae. Two of these, Aedes taeniorhynchus and Culex nigripalpus, have not been previously described as vectors of this parasite, while the third, Culex quinquefasciatus, has been implicated in other studies.