These bottom dwellers hatch and live under water for most of their lives - - 6 months to 2 years. They come out of the water, shed their skins and become winged adults that breathe air. These live only a few days or weeks, long enough to mate and lay eggs in the water. At night, the small water dwelling nymphs and larvae feed on algae ( and on each other ) on top of submerged rocks. During the day, they hide from fish under rocks. ( That is why fish feed best at dawn and dusk! )