RATES OF PREDATION BY CHRYSOMYA-RUFIFACIES (MACQUART) ON COCHLIOMYIA-MACELLARIA (FABR) (DIPTERA, CALLIPHORIDAE) IN THE LABORATORY - EFFECT OF PREDATOR AND PREY DEVELOPMENT

Chrysomya rufifacies (Macquart) is a blow fly that was recently introduced to North America. Because the larvae of this species are facultative predators on other maggots, native North American carrion flies probably will be negatively affected by the invasion. Cochliomyia macellaria (Fabr.), the native calliphorid with the greatest bionomic similarity to the invader, was selected as the prey species for a laboratory study of predatory behavior. We investigated the influence of both predator and prey development on predation rates when single predators and prey were paired in the laboratory. Third instar C. rufifacies consumed third and, at a lesser rate, second instar C. macellaria. Earlier instars were not predaceous. Both relatively small and relatively large third instar C. rufifacies consumed the same number of mid-size prey.