Observations on the Control and Ecology of Black Flies in Pennsylvania1

Abstract

A 12% solution of DDT in kerosene-xylene was applied by airplane at the rate of 1 lb. of DDT/acre over several areas. Large streams and open bodies of water were avoided, or treated only lightly, to prevent possible damage to fish. Complete control of black fly larvae was obtained at 34 stations in 15 streams out of a total of 35 stations in 16 streams. Pupae apparently were not affected by the spray. Adults were present in the breeding area immediately after the spraying but were not observed 1 week afterwards, although many had emerged from the pupae present at the time of spraying. Oviposition was not observed in the treated areas. Simulium venustum, S. vittatum, and Cnephia dacotense were the predominant spp. Small numbers of Prosimulium hirtipes, P. magnum, S. decorum, and S. costatum were also found. The more dense larvel populations were found immediately below the outlets of lakes, ponds, and bogs.