In 1996 and 1997 an attempt was made to determine the optimum time, if any, to treat cotton, Gossypium hirsutum L., for the cotton aphid, Aphis gossypii Glover, in Mississippi. Cotton (Sure-Grow 125 and NuCotn 33) at three different growth stages (pre-pinhead square or about 4th node, full-grown square or about 6th node, and first bloom) was treated twice at 7-day intervals with provado (0.053 l/ha) for aphids. The fourth treatment was an untreated control. All other insects were controlled in all plots. Results were somewhat inconsistent for the pinhead square and full-grown square treatments but showed that the bloom treatments produced significantly higher yields than the untreated check and the pre-pinhead square treatments but not the full-grown square treatments. All treatments made to NuCotn 33b yielded significantly higher than corresponding treatments made to Sure-Grow 125. Results were borderline as to economic feasibility of the treatments. Definite conclusions cannot be drawn as to the optimum time to spray for aphids without further experimentation.