Both dragonfly larvae and adult are carnivores, they will attack any preys within their territories. Larvae live in water and mainly feed on aquatic animals, such as mosquito larvae, tadpoles, small fishes, as well as the dragonflies which is laying their eggs on water surface. The diets of adult dragonflies are composed of flying insects, for instance, flies, mosquitoes and butterflies. The carnivorous dragonflies help to control the number of different species and thus support to attain equilibrium of species population in ecosystem. As dragonflies prey on mosquitoes and flies, which are pests of human, intense population of dragonflies serve as human's best defense against mosquito pests.

Common Bluetail is eating a little insect

A Green Skimmer is preying on Crimson Dropwing

Dragonflies locates at the middle part of food web, they are both preys and predators. Although they have very good eyesight and flying ability, they can still be caught by birds or even by spider webs. In Japan, China and Mexico, dragonflies are also served as secondary food source.

Dragonfly larvae are very sensitive to water quality, most of them can only survive in water without pollution. Dragonflies are valuable bioindicators, they are very visible in the wild and ease for survey. Regular monitoring of species composition and number of adult and larvae can help to manage wetlands systematically and effectively.