Field studies on the control of resistant house flies.

In 1959, Bayer Compound 29493 ( O, O -dimethyl O -(4-methylthio- m -tolyl) phosphorothioate), ronnel, and Dimetilan® (3-methyl-5-pyrazolyl dimethylcarbamate) were evaluated against resistant house fly populations in dairy barns and poultry houses. Bayer 29493 as a residual treatment, Dimetilan-impregnated fly bands, and ronnel-impregnated cords gave the most promising results. Effective control was obtained with Bayer 29493 applied at the rate of 50 milligrams per square foot. As a bait treatment, this compound did not give satisfactory control except in one instance. Dimetilan-impregnated fly bands, when installed at one dairy at the rate of 30 linear feet per 100 square feet of floor space, produced adequate control for more than 14 weeks. However, when installed at a second dairy at the rate of 6 linear feet per 100 square feet, satisfactory control was not obtained until 7 weeks after installation, after which fly counts remained below 21 for the balance of the season. The ronnel-impregnated cords (3/32-inch diameter) gave effective control within 2 to 4 weeks after installation in June and July, and this control persisted for the remainder of the season.