The Dragonfly

Article and photo by D.W. Cloud

The dragonfly is another amazing icon of creation. There are nearly 5,000 varieties, ranging in size from 3/4 inch to 7 1/2 inches. An extinct variety measured 30 inches from wing tip to wing tip.

Consider its life cycle. It hatches from an egg in a larval form called a nymph that lives in the water and breathes through internal gills. The nymph is ugly and colorless, but it has a “jet propulsion” system whereby it squirts water out rapidly to create fast movement when alarmed. After a few months to three years, the nymph crawls out of the water, begins to breathe air, attaches itself to the stem of a plant, undergoes metamorphosis in one night, and emerges from its larval body as a beautiful flying, air-breathing dragonfly. Though it has lived in the water all its life until this point, it is immediately an expert flyer and spends most of the rest of its life flitting through the air like an insect edition of the hummingbird.

Consider its eyes. It has two large compound eyes, each composed of up to 30,000 facets containing a lens installed at a perfect angle in conjunction with all of the other lenses. This gives it a nearly 360 degree field of vision. It also has three smaller simple eyes called ocelli on the top and front of its head. 80% of its mental processes are devoted to vision. It sees in color and can detect ultraviolet light. The dragonfly’s vision is so amazing that it is being studied by the Australian National University with the goal of improving robot flight. Dr. Richard Berry, who is in charge of this project, says, “The ocelli of dragonflies are exceptionally well tuned to provide fast, sensitive and directionally selective information about the world” (“Dragonfly Vision Could Aid Robot Flight,” Science Alert, Jan. 28, 2009).

Consider its wings. The wing membranes are thinner than paper and very strong. They are reinforced by veins or tubes only 1/10th of a millimeter thick, which act as “spars” for the wings as well as tubes for the cables of the nervous system and for the transportation of the blood fluid.

Consider its flying ability. It can fly up, down, sideways, or backwards and can change direction in an instant. It can glide. It can hover and then rapidly accelerate up to 35 miles per hour. It can beat each pair of wings together or separately; the rear wings can be out of phase with the front wings; and it can even move each wing independently, thus allowing for extreme maneuvers. It can catch other flying insects, such as flies and mosquitoes, in the air, either with its mouth or by forming a little basket with its legs and their bristly spines.

Its amazing neck muscles allow the dragonfly to move its head sideways 180 degrees, back 70 degrees, and down 40 degrees.

Consider its beauty. Dragonflies are brilliantly colored and typically are multi-colored. They can be green, yellow, blue, red, fuchsia, maroon, orange, pink, gold, and black. The colors come in earth tones as well as metallic varieties. These are formed in three ways: pigmentation (e.g., melanin produces yellows, reds, and browns), wax coating that diffuses light (similar to the coating on some shiny fruits), and light reflecting chitin scales, which perfectly diffract various parts of the light wave to create brilliant metallic colors.
Kathmandu Traveler
David W Cloud