The ability of several commercial spray adjuvants to extend the residual efficacy of Larvin 3.F and Ambush EC applications was evaluated through bioassays of second instar Helicoverna zea (Boddie) on cotton leaves removed hours, 3 days and 7 days after pesticide application. In addition, permethrin residues present on glass slides at these posttreatment intervals was determined by high-performance liquid chromatography. Bioassay mortality indicated that Nu-Film 17 was the most effective adjuvant for extending Larvin 3.F residues. Adjuvants did not appear to significantly affect Ambush 2EC deposits.