Dragonflies belong to the ancient Insect Order Odonata. Some dragonfly fossils date back to 250 million years. Drenched in hues of red, blue, yellow, green brown and black, they are some of the largest and most colorful insects on Earth. In proportion to their bodies, the wings, while transparent or nearly so, are quite large, spanning up to seven inches in some species. A tiny fretwork of strengthening cross-veins adds to their beauty. Ancient dragonflies were even larger, some with wingspans of more than two feet.
Dragonflies are voracious predators, both as adults and as immatures. Adults eat other insects, including mosquitoes, flies, bees, moths, butterflies and even other dragonflies. They catch prey in mid-air, often chasing them at speeds up to 18 mph before capture. Small prey is eaten in the wing, while larger prey are carried to a perch and consumed as the dragonfly rests. Adult dragonflies can eat as many as several hundred mosquitoes in a day, earning the well-deserved name of "mosquito hawks." But despite their size and speed, they do not bite or sting humans and are considered very beneficial to nature's balance.
Dragonfly immatures, called nymphs or naiads, are aquatic, depending on fresh or brackish water for survival. Nymphs feed on other aquatic insects including mosquito larvae, tadploes and small fish. Dragonflies are valuable as food for many animals and even a few plants. Birds, turtles, frogs, fish, spiders and other insects prey on them. Carnivorous plants such as sundews may catch and digest small adults.
Because the nymphs are aquatic, dragonflies can be found in abundance near freshwater habitats including ponds, lakes, rivers, streams, swamps, bogs, freshwater and brackish marshes, vernal pools and man-made ponds. These immatures live under water for a few months or as long as several years, then leave the water and molt into the beautiful winged adults. Despite their attachment to water, dragonflies are often spotted along roads and power lines and in fields, gardens and backyards, searching for food or an appropriate habitat. These energetic flyers travel great distances from their home waters and massive migratory swarms have been reported in late summer and early fall moving along seacoasts and lakeshores.
Winston H. Lavalle, PhD
Retired Professor of Biology
