Dragonflies and their close relatives called damselflies are ancient insects and prehistoric reminders of the age of the dinosaurs. Enormous dragonflies with a wingspread up to 30 inches across were part of the Peleozoic landscape about 300 million years ago. The largest insect ever known was a dragonfly called Meganeura monyi. It had a wingspread of 30 inches and a body 18 inches long. It lived until about 250 million years ago and then became extinct.
It is believed that prehistoric insects were much larger than modern day insects because of the high concentration of oxygen in the atmosphere, about 35 percent. That percentage has decreased since the days of the dinosaurs and is now about 21 percent.
Even with major changes in the landscape over millions of years, dragonflies have continued to adapt and are found worldwide. There are an estimated 5,500 to 6,500 dragonfly and damselfly species in the world. In Minnesota there are about 140 total species.
Dragonflies belong to the class Insecta and the Order Odonata. Odonata includes both dragonflies and damselflies. Dragonflies tend to be larger and have large eyes which meet in the center of their heads. The wings of dragonflies are transparent with assorted markings. They are not narrow at the base and the forewings and the hindwings are each shaped differently. When at rest, the wings are outspread. Damselflies are generally smaller than dragonflies and have a more slender body. Their eyes are widely separated, and they hold their wings together above their body when at rest.
Dragonflies are an aeronautical marvel. They can hover, glide, and pursue prey species like mosquitoes at speeds up to 29 inches per second. They are an aggressive and voracious predator that eats midges, mosquitoes, butterflies, moths, and even smaller dragonflies and fish.
The life cycle of a dragonfly has three stages: egg, larva, and adult. After hatching in a pond, dragonfly larvae become aggressive predators that eat "anything smaller than they are". The larval stage of a dragonfly's life can last anywhere from 2 months to 5 years. After emerging from the larval stage, adult dragonflies live only 4 to 6 months.
Although dragonflies are efficient predators, they also serve as prey for birds like purple martins, frogs, and larger dragonflies. The larvae are eaten by frogs, toads, newts and fish.
The largest species of dragonflies are the Lake Darner and Arrowhead Spike tail which average 3.1 inches long and the smallest dragonfly in the state is the Elfin Skimmer which is only .8 inches long.
Dragonflies and damselflies depend on abundant and diverse types of wetlands, rivers, and lakes. Every species has special requirements related to water quality, aquatic vegetation, and natural shoreline vegetation where they may lay eggs, hunt, or rest. They serve as an important part of the food chain and comprise an important part of our natural biological diversity. There are about as many dragonflies and damselflies in Minnesota as there are butterflies, but butterflies are more well known.
In order to better understand Minnesota's dragonflies and damselflies, the DNR's Nongame Wildlife Program has initiated an annual volunteer dragonfly survey so private citizens can help collect information on the distribution of the state's dragonflies. More information is available from www.mndragonfly.org.