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Abstract:
Except Chironomidae and Simuliidae, Diptera caught in emergence traps on two different types of streams in Lower Austria have been studied during the period 1972-1974. The respective communities are listed and listed and described. Abundance and weight (dry organic) are indicated and compared with results of comparable studies on emerging insects in Schlitz and Bonn (FRG). Only Limoniidae, Empididae and Dolichopodidae are of interest concerning their weights. Phenological and ecological aspects, especially of Empididae, are presented and discussed. Wiedemannia thienemanni n.sp., a new empidid, from Schrierbach is described. Species richness of five streams in West Germany and Austria, investigated with emergence traps are compared, and the connection with biotic and non-biotic factors is briefly discussed. Numbers of species rise with growing variablility of factors, but abundance and biomass of single years differ very much from the long term mean values.
