Abstract
The flight mill performance of 1-, to 18-day-old laboratory-reared screwworm flies, Cochliomyia hominivorax (Coquerel), was studied as a measure of fly vigor. Variation of flight performance among individuals was great. Generally, young screwworms were poor fliers, but their flight performance improved during the 1st wk after emergence. Females were generally stronger fliers than males in time and distance traveled. There was a linear correlation between the age of flies and the percentage of individuals with partial or complete loss of wings.