Results, which have been secured since 1922 on the investigation of the codling moth, Carpocapsa pomonella , to determine what type of nozzle and what pressure places the greatest amount of arsenic in the lower calyx cup of apple blossoms, are given in this paper. These data show that a fine mist spray under 100 pounds pressure places the most arsenic in the calyx cup, though not a great deal more than in the case of coarser sprays with higher pressures. The average amount placed in the calyx cup in thorough orchard spraying work is sufficient to prove a lethal dosage for the small apple worms which attempt to enter at the calyx end of the fruit.