Field experiments were conducted from 1957 through 1959 to determine the effect of phorate in controlling insects on wheat. A randomized block design with all treatments replicated four times was used. Plots were seeded with a grain drill and harvested with a combine. Few insects infested the plots in 1957, but in 1958, heavy infestations of the hessian fly, Phytophaga destructor (Say), the apple grain aphid, Rhopalosiphum fitchii (Sand.), and the English grain aphid, Macrosiphum granarium (Kby.), were encountered. Phorate was applied as a seed treatment to control these insects in the fall. To control the spring brood of hessian fly and also aphids that might infest the plots, granulated phorate was broadcast in early April. Experiments were also conducted to determine the effect of the seed treatment under simulated conditions of grazing by clipping. The phorate seed treatments caused significant losses in stand through reduced germination. However, such losses were not reflected in reduced yields. Both hessian fly and the aphids were controlled with a seed treatment of 0.5 lb. of phorate per 10C 1bs. of seed. The spring brood of hessian fly was controlled by granulated 10% phorate broadcast at the rate of 1.75 lbs. of toxicant per acre. Highly significant increases in yield were obtained with all treatments where insects were controlled. All plots clipped to simulate fall grazing yielded from 4 to 6 bushels more per acre regardless of treatment.

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