More than 32,000 fertilized eggs from Erythemis simplicicollis (Say), Libellula cyanea Fabr., L. incesta Hag. and Perithemis tenera (Say) were maintained at several regimes until eclosion. Between 20-35°C, development was progressively faster at each higher temperature; at this thermal range incidences of successful eclosions were also highest. At 15°C hatching was either greatly delayed or prevented, and at 40°C, no eclosions were noted; these temperatures mark the approximate lower and upper thermal thresholds for eclosion in these spp. Hatching peaks occurred during the first 1-3 days of the eclosion period. Numbers of eggs per clutch varied widely within and between spp.; clutch sizes ranged from a mean of620 for E. simplicicollis to 1366 for L. cvanea.