The tarnished plant bug (TPB), Lygus lineolaris (Palisot de Beauvois), has been a devastating insect pest in cotton agroecosystems in mid-southern cotton for several decades. Similar to related Heteropteran insect pests, L. lineolaris uses piercing-sucking mouthparts to penetrate harvestable fruiting structures on the cotton plant (i.e., squares, flowers, small bolls) leading to significant reductions in lint yield when infestations are above economic injury levels. Economically damaging infestations of L. lineolaris have occurred in Virginia and North Carolina cotton since 2013. In response, cotton area sprayed with broad-spectrum insecticides for L. lineolaris has increased in these states. As such, this dissertation research sought to answer a variety of questions to address this issue including 1) mapping the spatiotemporal abundance of L. lineolaris across Virginia as well as creating models to predict landscape and climate factors increasing infestation risk, 2) using a systems approach to provide growers with cost-effective and sustainable integrated pest management (IPM) solutions including economic spray thresholds, 3) investigating the incidence and transmission of fungal pathogens by L. lineolaris increasing Fusarium hardlock disease, further impacting yield loss at harvest, and 4) conducting insecticide resistance monitoring of L. lineolaris across the Southeast including biochemical lab assays to determine possible mechanisms of insecticide resistance. These findings will help form compressive IPM and insect resistant management (IRM) plans to equip southeastern cotton growers with practical management tools as well as useful information on "high-risk" areas to invest management resources, increasing economic returns while minimizing environmental impacts of over-spraying foliar insecticides. / Doctor of Philosophy / The tarnished plant bug (Lygus lineolaris) is an important pest in cotton from July through September that causes reduced yields and lower quality of lint and seed. Tarnished plant bugs cost the cotton industry hundreds of millions of dollars in losses annually. However, tarnished plant bug infestations were rare and sporadic in Virginia and North Carolina before 2013. In recent years, tarnished plant bug infestations have nearly doubled in these states, and research is needed to better understand how to manage recent pest outbreaks to avoid substantial economic losses. To address this issue, this dissertation research investigated a variety of questions including 1) the distribution of tarnished plant bugs in this region and the effects of geography and climate on infestation risk, 2) best practices for managing this pest in cotton fields, 3) possible associations between tarnished plant bugs and cotton boll diseases further impacting yield, and 4) whether tarnished plant bugs in this region are resistant to frequently used broad-spectrum insecticides as well as potential mechanisms driving resistance levels. Findings from this research will equip southeastern cotton growers with regionally specific recommendations for managing and monitoring tarnished plant bugs that minimize management costs and increase the quality and quantity of cotton yields.