The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is one of the most economically important pests of cotton, Gossypium hirsutum L., in the mid-southern U.S. Experiments were conducted during 2012 and 2013 to evaluate the effect of nitrogen fertilizer application rate on tarnished plant bug populations and management as well as cotton growth, development, and yield. Fertilizer (N) was applied as a 32% urea ammonium nitrate (UAN) solution at pinhead square at five different application rates: 0, 45, 90, 134, and 179 kg N ha-1. Plots were managed for tarnished plant bug with insecticides using treatment thresholds recommended by the Mississippi State University Extension Service. A corresponding set of plots for each N fertilizer application rate were not treated with insecticides fto determine tarnished plant bug infestation level and subsequent damage. The interaction of N fertilizer application rate and tarnished plant bug management level (treated or not treated) was significant for total number of plant bugs observed during the growing season. Fertilizer N application rate and tarnished plant bug management each had a significant impact on the mean number of plant bugs observed on a weekly basis and cotton lint yield. Fertilizer N application rate had a significant impact on the number of applications required to manage tarnished plant bug populations. This research demonstrated that there was an optimal level of N availability to balance yield and insecticide applications for tarnished plant bug, thus maximizing profits.