Thoracic sutures are ruptured by downward pressure from legs and wings, and the emerging adult usually reaches the stream surface in an air bubble. Emergence can be quite brief, requiring from 3-5 minutes. Some species emerge at night or during dawn or dusk, but many species emerge primarily during the day. Adult blepharicerids show a diversity of habits. The food of males and nonmandibulate females is unknown, but nectarivory is likely in some species.
Few species venture much beyond the riparian zone.
Knowledge of adult activity is poor for most species, even some that are widespread and common. Mating typically occurs soon after emergence and oviposition shortly after copulation. Small clusters of eggs are cemented to wetted or emergent rocks. In some species, the female crawls beneath the water and oviposits on submerged rocks. Larval blepharicerids constitute a guild of highly specialized grazers in streams.