The Status of fly resistance to insecticides in the Savannah area and its implications in the general problem of fly control

The development of resistance to DDT by house flie s was first reported in Italy in 1948. At least some of the numerous complaints concerning the lack of effective fly control with DDT in this country in 1947 and 1948 were undoubtedly due to fly resistance, although that fact w as not generally recognized at the time. By the early spring of 1949, however, the existence of DDT-resistant strains of house flies in many localities of the United States had been recognized and proved by both laboratory and field tests. Studies were immediately begun by several research agencies to develop DDT substitutes and to study the possible development of resistance to these other potential fly insecticides.The area in and around Savannah, Ga., is one of the locations where DDT and other halogenated hydrocarbon insecticides have been used for the longest continuous period of time. The Savannah laboratory of Technical Development Services began testing DDT for fly and mosquito control in this area in 1944, with numerous homes and some dairies being treated that year. The following year, 1945, the fly control studies were extended to include not only dairies, but also restaurants, abattoirs, food processing plants, garbage dump areas, and other similar fly foci. These studies were continued on about the same scale in 1946 and 1947, with chlordan also being used on several premises. The Bureau of Entomology and Plant Quarantine of the U. S. Department of Agriculture also used some of the dairies near Savannah for fly control studies in 1945, 1946, and 1947.195