A full-season, threshold-based insecticide control program, primarily for boll weevils, Anthonomus grandis grandis Boheman, was compared to no insecticide control in irrigated cotton in the northern Texas Rolling Plains from 1993 to 1995. These two insecticide-use options were compared in three cotton varieties (Paymaster HS-26, TAMCOT HQ95, All-Tex Quickie) and two row spacings (30" and 40"). Cotton was planted in late April - early May each year. Net returns per acre were calculated for each treatment and used to determine the most cost-effective chemical and row spacing management option for each cultivar. Of the 29 insecticide applications for thrips, boll weevils, bollworms, Helicoverpa zea (Boddie), and cotton aphids, Aphis gossypii Glover, during the 3-year study, 23 (79%) were for management of boll weevils. Boll weevil damage was lowest in HS-26 in the 30" spacing and in Quickie in the 40" spacing; these cultivars produced fewer squares, and received less boll weevil damage, in these two row spacings, respectively, than did the other two cultivars. Average yields were higher in treated plots, but average net income was higher in untreated cotton. In the 30" row spacing, highest net return was obtained from untreated Quickie ($65.22/acre), while in the 40" row spacing, highest net return was obtained in treated HS-26 ($70.63/acre). In all other comparisons between treated and untreated cultivars, net returns were numerically higher in untreated plots. Insecticidal control of boll weevils should be tailored to the cultivar and row spacing utilized.