House fly resistance in the Savannah, Georgia, area and its influence on chemical-control measures.

Resistance levels of Musca domestica L. from dairies and chicken ranches near Savannah, Georgia, were determined for 9 compounds by use of the immersion technique. The quantity of toxicant required to kill 95% of the field strains of flies was from 2 to 69 times the amount required to give the same level of kill of a susceptible NAIDM strain. Five compounds―dimethoate, OMS-1211( O -(2,5-dichloro-4-iodophenyl) O,O -dimethyl phosphorothioate), resmethrin (OMS-1206), crotoxyphos, and Mobam® (benzo[b]thien-4-yl methylcarbamate)―applied as residuals to dairies failed to give effective control (grill index of 20 or less) for more than 2 weeks. However, space sprays of naled and resmethrin and liquid baits of dichlorvos were still effective in killing these resistant field strains of house flies.