Certain acaricides were tested in 1958 and 1959 as control agents for the European red mite, Panonychus ulmi (Koch), and the two-spotted spider mite, Tetranychus telarius (L.), according to three plans: (1) single acaricides alone at standard concentration in consecutive acaricidal applications; (2) two acaricides separately at standard concentration in alternate applications, and; (3) two acaricides mixed, with each at one-half standard concentration, in consecutive applications. Test data indicate that plan 3 is better than plan 2. The data also indicate that mixtures of two acaricides, will each at one-half standard concentration, give better control than the weaker of the two applied alone at standard concentration.