The cotton aphid, Arphis gossypii Glover, has become increasingly more difficult to control in recent years with recommended insecticides on cotton in the Mississippi Delta. Comparisons of aphid control with the organophosphate, Lorsban, and the pyrethroid, Capture, in small plot field experiments between 1990 and 1992 suggest some decline in percent aphid control by Lorsban and a very large reduction in percent control by Capture, especially after the first application of the season. Bioassay of cotton aphid susceptibility in 1992 to Lorsban and Capture over a 5 week period showed no change within season in cotton aphid susceptibility to Lorsban in aphids from untreated plots or from plots treated 4 times with Lorsban (0.5 lb [Al]/acre) or Karate (0.025 lb [Al]/acre). Susceptibility to Capture changed significantly between the first week (pretreatment) and fifth week (posttreatment, 4 applications) for aphids sampled from Karate treated plots.