EFFECTS OF AERIAL APPLICATION OF DIFLUBENZURON ON EMERGENCE AND FLIGHT OF ADULT AQUATIC INSECTS

Malaise traps were used to monitor emergence and flight distances of a dult Plecoptera and Trichoptera from headwater streams in tile Fernow Experimental Forest, West Virginia, before and after application of di flubenzuron. Diflubenzuron was applied to 2 stream catchments in May 1 992. Emergence and flight distances in 2 treatment and 2 reference cat chments were assessed with 5 traps placed at various distances from ea ch stream during April through September 1991 and 1992. The regression of the number of adults caught in each trap versus distance of the tr ap from the stream was compared among years and treatments for each sp ecies to determine if diflubenzuron affected adult emergence. The emer gence of the stonefly, Peltoperla arcuata Needham, during the first 4 mo after treatment was reduced in die treatment catchments compared wi th the untreated catchments. Adults of other species were not reduced in the treatment catchments during the period of study. However, addit ional detritivorous species might have shown an adverse effect if the monitoring had been extended through the period after diflubenzuron-tr eated leaves entered the streams.