Delicate, weak-flyin insectswith two or three long "tails" at hind end. Front legs very long, especially in males, which can be recognised by a pair of claspers at the hind end. Usually 2 pairs of wings with compex venation:hind pair always much smaller than forewings and sometimes missing. Wings held vertically above body at rest or partly open: cannot be folded back along the body. Antennae minute. Eyes larger in male than in female and sometimes much expanded to form turrets well above the rest of the head (turbinate condition). Adults do not feed. Mainly crepuscular or nocturnal and rarely found far from the water in which they grow.