Data on the life cycle of Hydropezrla crosbvi were collected from January, 1974, to March, 1976, in Clear Creek, Denton County, Texas. Laboratory investigation helped in establishing instar number, egg incubation and description, and first instar descriptions. Adult Hydroperla crosbyi emerge in February - March when water temperature increases to a mean of 15 C. Eggs undergo a diapause, hatching when decreasing water temperature reaches 18 C in October - November. Maximum growth occurs when water temperatures are coldest. Male and female nymphs undergo ca. 12 and 14 instars, respectively. Larvae of Simuliidae and Chironomidae are the preferred food items of nymphs throughout the growth season.