In order to determine if annual applications of insecticide for control of the pea aphid, Illinoia pisi (Kltb.), on the Eastern Shore of Maryland would show a profit, a 5-year experiment was begun in 1938 at the Ridgely Substation. In this experiment treatments for aphid control are to be made each year regardless of the extent of the infestation. The records herein reported represent the results of the first season.