Adults may feed little or not at all, or they may be predators of other insects or molluscs, take pollen and nectar, or feed upon the blood of vertebrates. Communities Diptera communities are usually very complex in all types of aquatic systems with many species separated by habitat, habits, season, and trophic role. Chironomids alone usually have over 50 species present at any undisturbed site. Diptera occur in deep lakes, saline and thermal waters and make up the majority of marine insects species. Many species increase in enriched waters with depleted oxygen.
Many species are small in size and they have very rapid growth and short life cycles.
Economic Importance Biting species may be serious pests and they may also serve as vectors of many diseases in man and animals. Many areas must have control programs. Some may damage agricultural plants in wet soils. Some bio-control agents of other pests. Fly larvae often make up the majority of the diet of predacious insects and vertebrates.