The synthetic pyrethroid, permethrin, was evaluated as a residual lawn spray for adult mosquito control. In small-plot trials, the residual toxicity of four permethrin formulations was similar. Effectiveness did improve with increasing dosage, particularly between 0.01 and 0.05 g AI/m2. At 0.25 g AI/m2 the residual activity of permethrin was much greater than chlorpyrifos, carbaryl, methoxychlor, iodofenphos and malathion, currently registered as lawn sprays. However, two other pyrethroids, fenvalerate and particularly cypermethrin were more effective than permethrin. Backyards were also treated with EC formulations of permethrin at 0.007 g AI/m2. In six trials, landing counts of Aedes stimulans group mosquitoes were reduced 72% the evening of application and 63% the following evening in four of the trials. Thereafter, the control obtained declined and became more variable. Foliage treatment with permethrin is a very promising method of adult mosquito control.
