Characteristics of Residual Insecticides Toxic to the House Fly

Abstract

The purpose of this study was to obtain pertinent information about the residual insecticidal value of chlorinated hydrocarbons applied to various surfaces that had been exposed to different field conditions. The investigations conducted in 1943 at Orlando, Florida, by Lindquist et al. (1944) showed DDT to possess a high degree of residual toxicity to the house fly. They also showed a difference in toxicity of DDT when applied to painted and to unpainted wood. The need for the study reported here became apparent to the author when certain of his field applications of residual toxicants failed to effect adequate insect control. The results of this study, it is hoped, may serve as a guide to persons who are seeking to control insects through applications of residual insecticides and who are concerned with residues on plants.  DDT was the most persistent insecticide tested. The residual toxicity of DDT emulsions was better indoors on porous surfaces, such as wood, brick, and Cellutex, than on glass and galvanized iron. Out of doors, residues were more persistent on the nonporous glass and galvanized iron panels.  In a study on newer insecticides, 1'4 and 497 on wood and glass produced residues of significant longevity with high toxicity. Other materials tested were less persistent.