June 26th, 2006

Streamside Companions
The Dragonfly
By Neil M. Travis, Montana

When I was a boy my mother called these insects the devil's darning needle, and she said that they could sew your mouth shut. I think she just wished that were true! I have also heard them called mosquito hawks which is a more apt description. Dragonflies belong to the order Odonata which is comprised of two suborders: Anisoptera - true dragonflies and Zygoptera - damselflies. While there are many differences between the two insects, the most visible difference in the adult insect is the way they hold their wings when resting. Dragonflies hold their wings horizontally outward and damselflies hold them folded parallel over their thorax.

The nymph stage of dragonflies, like the damselflies, is aquatic. Dragonfly nymphs or naiads are grotesque creatures with robust or elongated bodies. The color varies with the species and with the environment, but most are somber-colored. To aid in camouflage they may be covered with a dense growth of filamentous algae and debris. They are common in lakes and streams, and can be found in beds of submerged vegetation and on the bottom hidden among the detritus.

The naiad is quite an interesting creature. The labium, or lower lip of the naiad, has been modified for use as a food capturing device. It is very long, sometimes nearly one-fourth the length of the body. Normally it lies folded backward underneath the head and thorax. The front end of this structure is equipped with stout teeth. The naiad lies in ambush among the weeds or hidden on the bottom. When an unsuspecting victim, like a mayfly nymph, stonefly nymph or even a small fish, comes within range the labium shoots out and seizes it. The strong teeth hold the prey firmly and the labium retracts, pulling the prey into range of the mouth.

The naiads have one other interesting characteristic: they are jet propelled. The gills, unlike the gills of damselfly naiads and mayflies, are internal; that is, they are inside the abdominal cavity. Powerful muscles in the abdomen suck in water, push it past the gills, and expel it out the anus. When threatened or when in a hurry to move from one location to another, they can use this method to propel themselves forward. Some of the larger naiads can move quite a distance using this method.

Depending on the species, there is a wide range of size both in the naiads and in the adults. Mature nymphs of the more common species range between 15 and 45 mm. in length. Large adult dragonflies have a wing-span of four inches and a body length, from head to tail, of three inches.

Dragonfly adults are quite varied in color and size. They have four wings that are either transparent or banded with darker bands of color. Body colors range from bright red to dark blue, with many variations. Some are even banded.

In the northern states dragonflies only live one year. Unlike damselflies, the naiads do not hatch all at once, but singly over a period of days or even weeks in early summer. The naiads crawl out of the water on a reed, rock or any other object that projects out of the water. It secures itself with its powerful legs, the skin splits down the back, and the winged adult emerges. Barring any unforeseen accident, the adult insect may live until fall. Some of the larger dragonflies migrate, like monarch butterflies, but most live out their lives within a short distance of where they emerged.

Dragonflies, especially the larger species, are territorial. It is possible to find them in the same area, even resting on the same spot, for the entire season. They defend these territories from other dragonflies.

Dragonflies are carnivorous, capturing and eating a variety of insects while on the wing. They have two large compound eyes that comprise most of the head. The head also contains a pair of extremely sharp teeth that are used for devouring their prey. The larger species can deliver a nasty bite to those inquisitive enough to pick it up.

The dragonfly is another creature that shares our lakes and streams with us, and makes angling such a fascinating and rewarding sport. ~ Neil M. Travis, Montana

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