It takes 1~3 years for larvae to grow into adults, and adults can live for 8 months, mainly because of freezing to death. Dragonflies are carnivorous insects. It preys on flies, mosquitoes, leafhoppers, midges, small butterflies and other pests in agriculture, forestry and animal husbandry. Dragonfly is an important natural enemy insect beneficial to human beings. It can be used to monitor environmental pollution and has medicinal, edible and ornamental values. "Dragonflies touch water" is the biological feature of dragonflies laying eggs in water.

Dragonflies generally live in wet places, such as dams or ditches. This is because they need water to breed and prey. Dragonflies like to fly on water, because there are many insects to prey on. They can fly in ponds or rivers or in open fields. The development process of dragonflies is quite complicated, from egg hatching to adult, it needs molting many times. Larvae can prey on old and other small animals in the water, and sometimes the same kind will eat each other. Adults and larvae are carnivorous and eat many pests. Adults can not only prey on mosquitoes and flies, but also pests such as butterflies, moths and bees, so they are beneficial insects.