The soybean aphid, Aphis glycines Matsumura, has become a principal arthropod pest of soybean since its first detection in 2000. This species threatens soybean production through direct feeding damage and virus transmission. A diverse community of insect predators feed on soybean aphid in Michigan. Assuming the effects of these predators on soybean aphid biological control are additive neglects complex, potentially negative interactions that may occur between them, including intraguild predation. We measured the impact of intraguild predation on soybean aphid population dynamics by comparing aphid populations in microcosms without predators, with either Aphidoletes aphidomyza larvae or Chrysoperla carnea larvae present, and with both a Harmonia axyridis adult and either A. aphidomyza or C. carnea larvae. In cases where H. axyridis was present with larval A. aphidomyza or C. carnea, the ladybeetle acted as an intraguild predator. Despite intraguild feeding by H. axyridis, aphid populations were lowest in microcosms where both an intraguild predator and intraguild prey were present. Harmonia axyridis may also affect the foraging behavior of A. aphidomyza and C. carnea larvae, with both species exhibiting behavioral avoidance in the presence of this intraguild predator.