June 11, 1999

    Dragonflies

Dragonflies are relatively large and often beautifully colored insects that spend much time on the wing in darting and rapid flight.  They use their aerial ability to catch other insects for food.

An expert hunter, the dragonfly has a streamlined body and glistening wings that carry it at speeds of 30 miles per hour or more; each pair of wings strokes alternately, the front pair going up while the hind pair is going down, at a rate of 30 or 40 strokes per second.

Like hummingbirds, dragonflies can hover or suddenly dart upward, downward or to one side.  In spite of common superstitious beliefs to the contrary, they do not sting as they do not have a stinging apparatus.

Nymphs of dragonflies are aquatic and live in ponds or streams, where they feed on insects.  The spiny legs of the adults form a sort of basket under the thorax for catching prey.  The head swivels easily on the slender neck, and the huge compound eyes can see in nearly every direction, enabling the dragonfly to catch insects such as mosquitoes and gnats in the air.

Researchers who have marked adult dragonflies have found that many may live six to eight weeks.  Most species will produce a single generation a year with the eggs or nymphs overwintering.  Marking individuals has also revealed that some dragonfly territories are only as large as the average kitchen or living room.