Chaoborus spp is a small fly species that is found all over the world (except in Antarctica). The insect spends one to two years of its life cycle under water in a larval state, in lakes no deeper than 70 metres. Larvae spend the day in lakebed sediment and rise to the surface at night to feed. They are equipped with air sacs that they can adjust to alter their depth in the water so as to migrate upwards and downwards.