A survey investigating the composition of adult thrips species and the effect of preventive, at-plant insecticides on this composition was conducted at multiple locations across the U.S. Cotton Belt in 2009 and 2010. Small-plot experiments included insecticide seed treatments containing imidacloprid (Aeris®) or thiamethoxam (Avicta Complete Cotton®), in-furrow applications of the insecticide aldicarb (Temik®), and an untreated control (no at-planting insecticide). The species composition of adult thrips varied among all locations which included trials within Arkansas, Georgia, Louisiana, Mississippi, Missouri, North Carolina, South Carolina, Tennessee, Texas and Virginia. As was the case in previous studies, tobacco thrips (Frankliniella fusca [Hinds]) was the dominant species at most locations. This species comprised an even greater percentage of the species composition in cotton not treated with insecticide. Conversely, the percent composition of other species tended to increase in cotton treated with insecticide. These observations suggest that tobacco thrips are relatively more sensitive to these insecticides. Overall, aldicarb reduced populations of adults more than other treatments, particularly imidacloprid.