We hypothesize that herbivory by predators is affected by the complexity of their diet. Coleomegilla maculata larvae fed prey - Acyrthosiphon pisum or Ostrinia nubilalis eggs - consumed two to three times more plant tissue (pinto beans) than those fed a mixed diet (containing pollen substitute and prey-based components). Simple, prey-only diets appear to lack plant-based nutrients important to this predator.