The quinoxalines, Eradex and Morestan, were found to be very effective miticides in laboratory and orchard experiments with the latter the most toxic. Applied at the pink stage of apple bud development Eradex and Morestan gave excellent control of European red mite, Panonychus ulmi (Koch), and delayed the build-up of the apple rust mite, Vasates schlechtendali (Nal.), and the McDaniel spider mite, Tetranychus mcdanieli McG. Both miticides were also very effective when applied in summer. The rates of use for Morestan were established at 8 to 16 ounces of active ingredient per acre in concentrate sprayers and at 2 ounces per 100 gallons in handgun sprayers and at twice these rates for Eradex. Where Eradex or Morestan were the only miticides used in an orchard for four years, the control of the European red mite and the McDaniel spider mite was excellent, an indication that selection of a resistant strain had not occurred. Morestan was highly toxic to the predaceous phytoseiid mite, Neoseiulus caudiglans (Schuster). Morestan has not injured fruit or foliage when applied at the pink bud stage but has marked fruit when applied in summer especially when applied by high-volume handgun sprayer.