The effect of nectariless cotton varieties on tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), populations was studied in Washington and Sunflower Counties, Mississippi, in 1981 and 1982. Fifteen and 18 fields of nectariless cotton were paired with fields of nectaried cotton in 1981 and 1982, respectively. Field size ranged from 16.2 to 60.7 ha, and all fields were sampled weekly with a D-Vac insect collector from early-June through mid-July in both years. Adult tarnished plant bug populations were significantly lower in the nectariless cotton in overall mean numbers in both years, and nymphal populations were significantly lower in the nectariless cotton in 1981. Adult populations were lower in the nectariless cotton an average of 44.4 and 43.6% in 1981 and 1982, respectively, while the corresponding reductions in nymphal populations were 42.3 and 27.1%. These results demonstrate that nectariless cotton can suppress plant bug populations over a large area of cotton.