Field experiments were conducted to determine the impact of threecornered alfalfa hopper, Spissistilus festinus, (Say), in reproductive growth stage soybeans. High densities of threecornered alfalfa hoppers were examined in field cages to understand feeding on soybean. No significant yield losses were observed from threecornered alfalfa hopper feeding during reproductive growth stages. Sweep net efficiency studies were conducted in order to convert the densities used in field cages to a sweep net threshold. Field experiments were also conducted to determine the impact of threecornered alfalfa hopper injury to seedling cotton. Threecornered alfalfa hopper injury to seedling cotton plants impacts individual plant yield, but further research is needed to understand the ability for undamaged cotton plants to compensate for neighboring damaged plants.