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Abstract

Emergence traps were operated for eleven years on two streams in Erie County, Pennsylvania to collect adult aquatic insects. One of the two sites on one stream received sewage effluent for two years. Of the Psychodidae, the tribe Psychodini species Psychoda parthenogenetica, Tinearia alternata, and T. alternicula were dependent on the sewage waters. A total of 33 species in 15 genera were collected during this study. Quateiella interdicta, P. minuta, P. phalaenoides, Neoarismus niger, Threticus bicolor, Crenopanimerus quadripunctatus, Stupkaiella mastelleri, and Satchelliella scotiae were common species. The importance of sewage waters for the maintenance of certain species of the tribe Psychodini is evident. Through the long-term emergence sampling, the flight periods of adults were established. After 1983 at the site 90 m below the sewage outfall, there was a marked decrease of Psychodini, particularly Clogmia sp., undoubtedly due to the reduction of sewage effluent and high nutrient loading at this site. The recovery for populations of the tribes Telmatoscopini and Pericomini has not progressed very rapidly, possibly due to the flight distance required to reestablish populations and the long life cycle durations. (Rochester-PTT)