The problem of spider mite resistance to acaricides has stimulated interest in the use of petroleum oils as a means of mite control. In 1963, plots were established in a Red Delicious apple orchard to evaluate one new acaricide and several oils of varying viscosity and unsulfonated residue against the European red mite. Among several acaricides that had been studied in 1962, the most promising material was Morestan, a new cyclic carbonate insecticide.