Toxicity of certain new compounds to insecticide-resistant houseflies.

Houseflies in poultry ranches in certain areas of California are now resistant to most insecticides licensed for use in these establishments, and this resistance problem appears likely to spread to other areas in the future. The authors have therefore studied the contact and oral toxicity of 19 new compounds that have shown interesting properties against resistant flies. These compounds were selected from among several hundred submitted by various laboratories for evaluation under a co-operative programme sponsored by the World Health Organization.Five compounds were found to be as toxic to three insecticide-resistant strains as to a susceptible strain, and showed strikingly steep log-dosage/probit mortality lines against the resistant strains. The authors suggest that these compounds be further studied for fly control in field trials.