The purpose of these experiments was to study the function of the gustatory chemoreceptors of the blowflies, Cochliomyia americana C. & P. and Phormia regina Meigen. The gustatory sense organs of P. regina have been previously studied and reported on by Minnich (1926). Studies on the chemoreceptors of the tarsi and mouth parts of the primary screwworm fly, C. americana, which are gustatory in function, are here reported on for the first time. The tests on the adults of these species cover the normal responses to sucrose, responses to sucrose with mercuric chloride added, effects of age, and effects of sex on these responses.