The influence of an intercropped agroecosystem of oilseed rape, canola-type (Brassica napusL.), and field pea (Pisum sativumL.) on the population level of the flea beetle,Phyllotreta cruciferae(Goeze), was evaluated for 3 yr in east-central North Dakota. Treatments included two monocultures of oilseed rape (8 kg/ha of live seed) and field pea (200 kg/ha of live seed) and three intercropped mixtures of field pea to oilseed rape (150:2, 100:4, and 50:6 [kg/ha]). Flea beetle counts per 0.5 m2were highest in the oilseed rape monoculture in all 3 yr of the study but significantly higher from the other treatments in only one year. The sex ratio ofP. cruciferaeadults collected was not influenced by the treatments. The land equivalent ratios (LER = [intercropped yield for pea/monoculture yield for pea] + [intercropped yield for rape/monoculture yield for rape]) for the intercrop treatments did not exceed 1.0, indicating that the intercrops selected were not as efficient for yield as the monocultures. This intercrop system was not effective in reducing flea beetle loads on a per-plant basis, nor was there a yield advantage from this intercrop system.