Eleven insecticide treatments were evaluated for efficacy against cotton aphid. Treatments containing Bidrin, Metasystox-R, Lannate, or Provado provided in excess of 90% control at 2 DAT, but aphid populations recovered rapidly following treatment. Treatments providing best overall control were Bidrin at 0.5 lb AI/A and Lannate at 0.45 lb AI/A. Infestation level in the untreated check was extremely heavy, exceeding 800 aphids/leaf at one point and persisting at high levels for more than 3 weeks before being controlled by a natural fungal epizootic. This prolonged, heavy aphid infestation resulted in a yield reduction of 220 lbs. of lint per acre.