[Objectives]  The lady beetles Coccinella septempunctata and Hippodamia variegate are important and widely used biocontrol agents. Cannibalism in captive colonies of these species significantly reduces the number of insects produced for biological control so developing a rearing container that reduces cannibalism would be a significant advance in the captive husbandry of these species. [Methods]  Three different barriers (Con-A, Con-B and Con-C) were designed and placed inside plastic Petri dishes. Sixteen first instar larvae were reared in each container and the optimal design identified by comparing a series of parameters with empty Petri dishes as the control. [Results]  Larval cannibalism was obvious by the 5^th day but survival of C. septempunctata declined comparatively slowly in Con-C containers whereas survival of H. variegate was higher in all three types of experimental container compared to the control. More C. septempunctata adults were obtained from Con-C containers, which produced significantly more adult insects than the other two types of container and the control. More H. variegate adults were obtained from the three experimental containers than the control but this difference was not significant. Larvae of both species chose to pupate on the experimental barriers. Adults raised in Con-A containers were relatively large compared to those raised in the other containers, but size varied considerably between females and males. [Conclusion]  Barriers within plastic Petri dishes were effective in reducing cannibalism among C. septempunctata and H. variegate larvae at high density, a result that provides a foundation for developing effective and easy to use, rearing containers for these species.