Larvae are hatched in water where they spend their early phases of their lives. The naiads (juveniles) of Giant Stoneflies are incredibly sensitive to pollution and die off quickly in unclean waters. Biologists and fishermen and women use the presence of Giant Stoneflies as a mark, or indicator, of how clean the water is in that area.
Stoneflies are nocturnal creatures and generally live in areas near freshwater streams or rivers. Only the nymphs eat and they prefer to feed on algae and other plant material underwater. Adults do not eat at all.
Stoneflies, in general, can be attracted to artificial light in the late spring and early summer times of the year.