Tests were conducted to determine rates and time of application of Prep^® and Dropp^® and effects of early irrigation cutoff with chemical termination for reducing pink bollworm, Pectinophora gossypiella (Saunders), and boll weevil, Anthonomus Boheman, diapausing populations in Arizona and southern California. At Maricopa, Arizona, treatments with Prep^® at 1.0 or 1.5 lb/ac or Dropp^® at 0.05 or 0.1 lb/ac on Sept. 3 or Sept. 10 significantly reduced the number of green bolls and diapause pink bollworm larvae at harvest. There was no reduction in green bolls when the treatments were applied on Sept. 17. There were no significant differences in yields between the untreated check and any of the treatments; however, yields were slightly lower in the Sept. 3 treatments than the later dates. At Brawley, California, plots irrigated last on July 16 had significantly less yields than plots irrigated on Aug. 13 and Aug. 27, but plots irrigated last on July 30 had no difference in yields from later irrigations. There was no difference in yields when Prep^® at 1.0 lb/ac or Dropps at 0.04 lb/ac was applied ca. 2 weeks after the last irrigation on July 16. There was a significant reduction in green bolls due to irrigation cutoff with Aug. 27 > Aug. 15 > July 30 = July 16. The number of green bolls was reduced by the chemical termination treatments, but the reductions were significantly different only when the last irrigation was on Aug. 27. At Laveen, Arizona, Prep^® at 1.5 lb/ac was applied to 4 fields infested with boll weevils on Sept. 15, 23, and 29. All treatments significantly reduced the squaring rate, number of green bolls, number of developing boll weevils, and increased the percentage of open bolls. There was no reduction in yields by any treatments.