The Dragon-Flies and Damsel-Flies

Teacher’s Story

POND without dragon-flies darting above it, or without the exquisitely iridescent damsel-flies clinging to the leaves of its border would be a lonely place indeed. As one watches these beautiful insects, one wonders at the absurd errors which have crept into popular credence about them. Who could be so silly as to believe that they could sew up ears or that they could bring dead snakes to life! The queer names of these insects illustrate the prejudices of the ignorant—devil’s darning needles, snake doctors, snake feeders, etc. Despite all this slander, the dragon-flies remain not only entirely harmless to man, but in reality are his friends and allies in waging war against flies and mosquitoes; they are especially valuable in battling mosquitoes since the nymphs, or young, of the dragon-fly, take the wrigglers in the water, and the adults, on swiftest wings, take the mosquitoes while hovering over ponds laying their eggs.

The poets have been lavish in their attention to these interesting insects and have paid them delightful tributes. Riley says:

“Till the dragon fly, in light gauzy armor burnished bright,
Came tilting down the waters in a wild, bewildered flight.”

While Tennyson drew inspiration for one of his most beautiful poems from the two stages of dragon-fly life. But perhaps Lowell in that exquisite poem, “The Fountain of Youth,” gives us the perfect description of these insects:

In summer-noon flushes
When all the wood hushes,
Blue dragon-flies knitting
To and fro in the sun,
With sidelong jerk flitting,
Sink down on the rushes,
And, motionless sitting,
Hear it bubble and run,
Hear its low inward singing,
With level wings swinging
On green tasselled rushes,
To dream in the sun.

It is while we, ourselves, are dreaming in the sun by the margin of some pond, that these swift children of the air seem but a natural part of the dream. Yet if we waken to note them more closely, we find many things very real to interest us. First, they are truly children of the sun, and if some cloud throws its shadow on the waters for some moments, the dragon-flies disappear as if they wore the invisible cloak of the fairy tale. Only a few of the common species fly alike in shade and sunshine, and early and late. The best known of these is the big, green skimmer, which does not care so much for ponds, but darts over fields and even dashes into our houses, now and then. Probably it is this species which has started all of the dragon-fly slander, for it is full of curiosity, and will hold itself on wings whirring too rapidly to even make a blur, while it examines our faces or inspects the pictures or furniture or other objects which attract it.

Another thing we may note when dreaming by the pond is that the larger species of dragon-flies keep to the higher regions above the water, while the smaller species and the damsel-flies flit near its surface. Well may the smaller species keep below their fierce kindred, otherwise they would surely be utilized to sate their hunger, for these insects are well named dragons, and dragons do not stop to inquire whether their victims are relatives or not. It is when they are resting, that the dragon and damsel-flies reveal their most noticeable differences. The dragon-fly extends both wings as if in flight while it basks in the sun or rests in the shadow. There is a big, white-bodied species called the whitetail which slants its wings forward and down when it rests; but the damsel-flies fold their wings together over the back when resting. The damsel-flies have more brilliantly colored bodies than do the dragon-flies, many of them being iridescent green or coppery; they are more slender and delicate in form. The damsel-fly has eyes which are so placed on the sides of the head as to make it look like a cross on the front of the body fastened to the slender neck, and with an eye at the tip of each arm. There are very many species of dragon and damsel-flies, but they all have the same general habits.

The dragon-fly nymphs are the ogres of the pond or stream. To anyone unused to them and their ways in the aquarium, there is a surprise in store, so ferocious are they in their attacks upon creatures twice their size. The dragon-fly’s eggs are laid in the water; in some instances they are simply dropped and sink to the bottom; but in the case of damsel-flies, the mother punctures the stems of aquatic plants and places the eggs within them. The nymph in no wise resembles the parent dragon-fly. It is a dingy little creature, with six queer, spider-like legs and no wings; although there are four little wing-pads extending down its back, which encase the growing wings. It may remain hidden in the rubbish at the bottom of the pond or may cling to water weeds at the sides, for different species have different habits. But in them all we find a most amazing lower lip. This is so large that it covers the lower part of the face like a mask, and when folded back reaches down between the front legs. It is in reality a grappling organ with hooks and spines for holding prey; it is hinged in such a manner that it can be thrust out far beyond the head to seize some insect, unsuspecting of danger. These nymphs move so slowly and look so much like their background, that they are always practically in ambush awaiting their victims.

The breathing of the dragon-fly nymphs is peculiar; there is an enlargement of the rear end of the alimentary canal, in the walls of which tracheæ or breathing tubes extend in all directions. The nymph draws water into this cavity and then expels it, thus bathing the tracheæ with the air mixed with water and purifying the air within them. Expelling the water so forcibly, propels the nymph ahead, so this act serves as a method of swimming as well as of breathing. Damsel-fly larvæ, on the other hand, have at the rear end of the body, three long, plate-like gills, each ramified with tracheæ.

Nymphs grow by shedding the skin as fast as it becomes too small; and when finally ready to emerge, they crawl up on some object out of the water, and molt for the last time, and are thereafter swift creatures of the air.

References—American Insects, Kellogg. Comstock’s Manual.