The species composition and seasonal occurrence of alate aphids was determined during 1990 in cotton plots planted at different times during the growing season. For the predominant species found in the cotton plots, the seasonal and diurnal pattern of occurrence in aerial samples collected with a 28-foot high Johnson-Taylor type suction trap were also determined. Between mid-April and late May, the predominant species that effectively colonized the cotton plots were the cotton aphid, Aphis gossypii Glover and the cowpea aphid, Aphis craccivora Koch. Starting in early,June and for the remainder of the growing season, the cotton aphid was the only species that was consistently present in the plots. Three periods when alates of the cotton aphid were abundant in the plots were from mid-April to late May, late June to late July and after late August. The suction trap samples indicated three periods of increased aeiral activity of the cotton aphid. The first period from mid-April to late May consisted of four peaks and coincided with the initial colonization of the cotton plots. The second period which was greater than the first extended from early July to early August and corresponded to the period when large numbers of alates were produced in the cotton Plots. The final period was from mid-September to early October and was apparently associated with dispersal from mature cotton. Three similar periods of increased aerial activity were also observed for the cowpea aphid; however, the highest activity was observed during early season from early April to late May which corresponded to its occurrence in the cotton plots. A minor period of aerial activity was observed in late July and early August and activity again increased in early September and thereafter. Cotton aphid captures at 2-hour intervals in the 28 foot suction trap indicated a bimodal pattern with peaks for the 2-hour intervals between 0800 and 1000 and between 1800 and 2000 hours (CST, Daylight Savings Time). Very few cotton aphids were captured between 2200 and 0600 hours. A similar bimodal pattern of captures was observed for the cowpea aphid except that the first peak was observed in the interval between 1000 and 1200 hours.