Stickiness of western growth U. S. cottons has been a sporadic problem of varying severity during the past decade, but the stickiness of the 1986 crop San Joaquin Valley cottons far surpassed that of any previous year within memory. The problem devastated mills that processed this cotton. The nature of the stickiness in processing indicated that random, heavy sticky spots, charactistic of insect contamination, not uniform contamination such as from natural plant sugars, were the cause of the stickiness. Commercial cottons and cottons from the Acala Cotton Board Variety Testing Program were obtained and studied to determine causes and distribution of the stickiness. Preliminary findings indicate that stickiness occurred randomly throughout the valley and across varieties. More than two-thirds of the hundreds of samples tested were sticky. The cause of the stickiness has been identified, tentatively, as honeydew contamination from late season aphid infestations.