The soybean aphid, Aphis glycines, is a recently invaded soybean pest in North America. Natural enemies found attacking soybean aphid include coccinellids, predatory hemipterans, and parasitoid hymenopterans. The parasitoid Lysiphlebus testaceipes attacks soybean aphid in the field, but produces relatively low parasitism rates. One possible explanation for the low parasitism rates in the field is intraguild predation (IGP) on L. testaceipes mummies (pupae) by other natural enemies. Orius insidiosus and Harmonia axyridis are two of the likely intraguild predators, as they are both generalists that have been found to feed on L. testaceipes mummies in the laboratory. To test the hypothesis that IGP is operating in the field, we conducted a manipulative field study in the summer of 2005 to determine the amount of IGP directed against L. testaceipes. The field study included 6 six treatments as follows: (i) a 1x1 m predator exclusion cage treatment, (ii) a sham cage that allowed predator movement in and out of the cage, and (iii) a no cage control. These 3 treatments were either subjected to a L. testaceipes release or not in a fully crossed design. In addition, we collected predators from the open field and sham cage sites and did PCR-based gut content analyses to determine which predators used L. testaceipes as prey.