This study, the first in an intended series of anatomical investigations of the blister beetles, was undertaken primarily for the purpose of determining the changes that occur in the skeletal musculature during postembryonic larval development. The species studied, Epicauta segmenta (Say), like others belong ing to the coleopterous family Meloidae, is characterized by hypermetamor phosis (SELANDER and WEDDLE, 1969). The egg develops into an active, well sclerotized larva that searches for grasshopper eggs, which, as in the case of all species of Epicauta, serve as the sole larval food. This...