The developmental and reproductive fitness of the polyphagous predator Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) was compared on two factitious foods and four artificial diets. Adults fed factitious foods (Ephestia kuehniella Zeller eggs and Artemia franciscana Kellogg cysts) performed better than those fed artificial diets. Among the artificial diets, a diet composed of liver and ground beef scored better than meridic diets based on egg yolk. Within the egg yolk-based artificial diets, the developmental fitness varied proportionally with the amount of egg yolk present in the diet. A food switching experiment, in which nymphs and adults of the predator were fed either E. kuehniella eggs or an egg yolk-based artificial diet, showed that the impact of adult food on reproductive capacity was greater than that of nymphal food. An optimal adult food was able to wholly compensate for deficiencies incurred by an inferior artificial diet in the nymphal stage. A strong correlation was found between oocyte counts, lifetime oviposition, and the number of eggs laid after 8 d. A rapid dissection assay may thus be effective to reliably and economically assess the fitness of O. laevigatus as a function of the diet. This method also may prove useful as part of quality assurance procedure for commercially produced predators.