The ability of soybean loopers, Pseudoplusia includens, (Walker), to selectively feed on meridic diet with different concentrations of Cry1Ac was investigated in a choice assay. Neonates selected non-treated meridic diet and diet with concentrations of Cry1Ac ranging from 0.1 to 1.0 μg/mL for feeding compared to diet with Cry1Ac concentrations of 5.0 and 10.0 μg/mL. Averaged across rating periods, means of 11.9 to 17.6% of larvae were observed feeding on diet with Cry1Ac concentrations ranging from 0.0 to 1.0 μg/ml, compared to 3.4% on diet with Cry1Ac concentrations of 5 μg/mL and 4.3% at 10 μg/mL. In a no-choice study, concentrations ranging from 0.1 to 1.0 μg/mL produced 4.3 to 40.8% mortality in soybean looper; while, concentrations of 5.0 μg/mL produced 58.5% mortality and 10.0 μg/mL produced 90.8% mortality. Also, diet with Cry1Ac concentrations of 5.0 and 10.0 μg/mL delayed the development of soybean looper larvae compared to diet with the other concentrations of Cry1Ac. Based on results of this study, soybean loopers can select diet with concentrations of Cry1Ac that result in low (<50%) levels of mortality.