The Trichoptera of the lower Orange River were collected at irregular intervals from 1993 to 2008. A total of 15 species are listed, including a new species which is described as Catoxyethira gariepensis n. sp. (Hydroptilidae). The composition of the taxocenosis and the dominant species at different sample sites are briefly documented. The survey has revealed the occurrence of a poor fauna, which consists mainly of widespread species. Records from the literature and the present data are summarised. Twenty-six species are now known to occur in the Orange River. Droughts and flash-floods are major events in this watershed. These are unpredictable and contribute to the unstable conditions of the river ecosystem and do not allow the development of a more diverse fauna. Keywords: Trichoptera, faunistics, Catoxyethira gariepensis spec. nov. (Hydroptilidae), taxonomy, Orange River, Fish River, flash-floods, drought periods, Namibia, South Africa.