A dragonfly is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body.
Dragonflies typically eat mosquitoes, midges and other small insects like flies, bees, and butterflies. They are usually found around lakes, ponds, streams, and wetlands because their larvae, known as "nymphs", are aquatic. Dragonflies do not normally bite or sting humans; in fact, they are valued as a predator that helps control the populations of harmful insects, such as mosquitoes.
Dragonflies have very good eyesight due to their eye structure. Dragonflies have up to 30,000 facets to their compound eyes; each one is a separate light-sensing organ, arranged to give nearly a 360° field of vision.
Dragonflies are the world's fastest insects, capable of reaching speeds of up to 60 mph. The Common Green Darner dragonfly (Anax junius) is nicknamed "Darning Needle" because of its body shape. It is one of the biggest and fastest-flying dragonflies, able to reach speeds of 53 mph. A study showed that dragonflies can travel as much as 85 mi in one day.
Information source: Wikipedia