THE RESISTANCE of insect and spider mite pests of grapevines in many areas of the San Joaquin Valley to insecticides has led to the use of combinations of insecticides and often to more frequent applications for control. In view of the history of the use of combinations of chemicals for control of insecticide-resistant pests, these insects and spider mites may soon become resistant to the combinations now in use. Although a great many combinations may be tried and some new ones may be found effective, grape growers need additional and more effective acaricides. To this end, many newer chemicals (not registered for use on grapes) have been tested in the field for the past several years. Some of these are nearing registration and general use; however, the University of California does not have sufficient information to recommend any of these new materials for use on grapevines at the present time.