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Archive - September 2018
What are Dragonflies?
Dragonflies are insects. Insects have three pairs of legs and two pairs of wings. Their body has three sections: head; thorax; and abdomen.
What Do They Look Like?
Dragonflies have three stages in their life cycle: egg; nymph; and adult. The nymph lives in water. It has a wide, oval or round abdomen, large eyes and a double-hinged lower lip. There are two pairs of wing pads and three, short, pointed structures at the end of the abdomen. The nymph is brown or green and has six legs.
An adult dragonfly has two pairs of membranous wings and six legs. The wings are alike in size and shape. They hold the wings in a horizontal position when they are not flying. The abdomen is long and slender. Their compound eyes are very large.
How Big Are They?
Dragonfly nymphs in Illinois may be from about one-half inch to a little more than two and one-fourth inches in length. The largest adult dragonflies today in Illinois are about four inches long. Some ancient dragonflies in Illinois had a wingspan of more than three feet!
Where Do They Live?
Dragonflies can be found statewide. The nymph lives in ponds, lakes, marshes and streams. The adult can be found near ponds, lakes, marshes and streams.
How Do They Reproduce?
Dragonflies mate while flying. The female of some species lays the fertilized eggs on the surface of the water. These eggs then sink to the bottom of the water body and develop there. The female of other dragonfly species lays fertilized eggs on aquatic plant stems. One generation per year is produced, but development may take three years or more depending on the water temperature and the amount of food available.
What Do They Eat?
The nymph feeds on other insects, worms, mollusks, crustaceans and small fishes. Adult dragonflies eat other insects.
Does Anything Eat Dragonflies?
Many fishes eat dragonfly nymphs. Frogs and birds eat dragonfly adults. Fishes and spiders will eat the adults, too, if they can catch them.
What Else Should I Know About Them?
About 147 types of dragonflies have been identified in Illinois. Their wings flap alternately, allowing them to hover and fly backwards. Adults move very quickly. Their normal flight speed is about 25 miles per hour, but they can reach 75 miles per hour for short bursts. Adults live a few weeks to a few months. One species of dragonfly, Hine’s emerald dragonfly (Somatochlora hineana) is endangered federally and in Illinois. Another dragonfly species, the elfin skimmer (Nannothemis bella), is threatened in Illinois.