Insecticide applications to control tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), during cotton, Gossypium hirsutum L., bud formation are common throughout the Midsouth of the United States. Cultivation practices and the pest complex have changed since action thresholds were established for this pest. A trial was conducted at 33 locations over 3 yr throughout the Midsouth to evaluate tarnished plant bug damage to cotton during the prebloom period. There was no consistent yield response to action thresholds, but average tarnished plant bug density and average square loss were both significant factors impacting lint yield. Based on the yield responses and application frequency of the various action thresholds, the best economic scenario occurred when tarnished plant bug density during the prebloom period averaged eight per 100 sweeps and square retention averaged 90%. The action thresholds required to achieve these averages are expected to be higher than these levels because pest pressure is not normally constant during the prebloom period. When insecticides are required, an application interval shorter than one week may be needed to obtain satisfactory control.