We determined the community composition of Carabidae in maize in Pennsylvania to range from 35 to 45 species, and defined dominant species based on abundance for major feeding guilds during distinct plant phenological stages. Community composition was dynamic. Among predatory species, Scarites quadriceps was dominant early, and this shifted to Pterostichus melanarius and Poecilus chalcites by midseason. Harpalus pensylvanicus was the dominant weed seed feeder. We then studied how pest management choices influenced the population dynamics of dominant species in both field and sweet corn. We compared dynamics measured by weekly pitfall traps in split plot experiments. Main plots were genotype (transgenic or isoline) and insecticide management (with or without soil insecticide for field corn, and soil/foliar insecticide for sweet corn). The split plot factor was crop type (field corn and sweet corn). The influence of both management and transgenic/isoline cultivar on community and population dynamics is discussed for both sweet and field corn.