The Aouali and Damour watersheds include the main river systems of southern Lebanon. Seven species of Simuliidae were collected from 27 sampling stations along these streams.Simulium nihan. sp. is described; it is related to the species of themonticola‐group. Three species have a restricted distribution within these streams, two of them being crenobiont. The others extend over wide altitudinal and ecological ranges.Eusimulium latizonum, Wilhelmia pseudequinaandSimulium nitidifronsare the dominant species of the black‐fly community.