The effect of a preplanting application of phorate onTetranychus urticaeKoch, associated predators, and aphids on strawberry was investigated in southern California in 1969–70. The spider mite population was significantly lower in the phorate plot from March 3–April 28, reaching a peak averaging 226.8 active stages per leaflet on May 5, compared to 445.5/leaflet in the check on April 28. Except for March 24 and April 14, the predator population was significantly higher in the check plot from March 17–May 12.Scolothrips sexmaculatus(Pergande) andGeocorisspp. were the most common predators present. The seasonal mean number of spider mites and predators was significantly lower in the phorate plot and the mean fruit yield (g/plant) was significantly higher. The aphid population never exceeded an average of 0.3 aphids per leaflet in the phorate plot compared to a peak of 59.2/leaflet in the check on March 24. The strawberry aphid,Chaetosiphum fragaefolii(Cockerell), comprised 96% of the aphid population. The use of phorate in an integrated control program for strawberry pests is discussed.