Control of Farm Flies in Malta—I. Toxicities of insecticides to laboratory and Maltese field strains of Musca domestica and Stomoxys calcitrans

The results of bioassays using the WHO topical application method are given for 25 insecticides against susceptible laboratory strains of Musca domestica L. and Stomoxys calcitrans L. Many of these were also assayed against M. domestica and S. calcitrans (13 and 9 insecticides respectively) collected from farms in Malta. Comparisons of median lethal doses show resistance of Maltese M. domestica to DDT, dieldrin and malathion as well as increased tolerance to trichlorphon and fenchlorphos. Monitoring tests in subsequent years showed an increase in the tolerance to trichlorphon and fenchlorphos of Maltese M. domestica.