Two winged flies live through a complete metamorphosis life cycle. Eggs hatch into larvae which can vary in size and shape considerably from maggot shape to worm like. Often gills or breathing tubes are visible on aquatic larvae which then turns into a pupa that can swim to the surface and shuck where the adult winged fly emerges. The main stages of interest to the fisherman is the pupa stage which is imitated by buzzers or emerger patterns and the adult stage with either a small wet or dry fly.