Studies of European red mite populations (Paratetranychus pilosus) in replicated field plots over a period of 5 yrs. are reported. Summer applications of sulfur, regardless of the type used, were ineffective in holding red mite population]! in check; the less sulfur used in the spray schedule, the less red mite injury may be expected. This seems to be due to the comparative inefficiency of sulfur in killing mites and its efficiency in killing the mite predator, Seius sp. Limited tests indicate Fermate acts in a similar manner. Most effective mite control can be obtained by the application of a dormant oil spray supplemented, when injury threatens, by application of a summer oil, 1 to 1, or a summer dinitro used according to directions.