Population Movements of Adult Trichoptera at a South Swedish Stream

110 species of adult Trichoptera were trapped at a South Swedish stream. Breeding localities were found for 54 species, 34 of which inhabited the stream system. Emergence of some species also occurred in the uppermost parts of the stream. 97 % of the adults in non-attracting traps were lotic species. In these traps 55 % of all individuals were intercepted when moving upstream and 45 % when moving downstream. About the same proportion was found for individual species, including the dominant Potamophylax cingulatus Steph. In Rhyacophila fasciata Hag. upstream movements were much greater than downstream movements. Some lotic limnephilids dispersed widely from the stream and exchange with neighbouring populations probably occurred. Dispersing females had generally mated and were egg-bearing.