You should not keep butterflies and praying mantises in the same habitat at the same time. Praying Mantises are predators, and their instincts would lead them to prey upon the butterflies if they were in the habitat simultaneously. These projects are best completed in separate time periods or with separate habitats. Praying Mantises are such voracious predators that they sometimes will eat each other! That's why we recommend you release the majority of your mantises and only keep one to raise.