Tests at State College, Mississippi, in 1941 indicated that nitrogenous fertilizer applied under the plants at time of planting caused an increase in aphids where the cotton was dusted with Ca arsenate, but not where Ca arsenate was not applied. Dusting with Ca arsenate caused a significant increase in aphids in all tests, but where both fertilizer and Ca arsenate were used the increase was greater and was roughly in proportion to the N content of the fertilizer.