Dragonflies and Damselflies

This is how you know if you are looking at a damselfly or a dragonfly; look at the wings. Each member of the dragonfly family extends both wings out like airplane wings while it basks in the sun or rests in the shadow.There is one big, white-bodied dragonfly species called the whitetail which slants its wings forward and slightly down when it rests; but its wings are still out to the sides, not over its back. The damselflies all fold their wings together above and over their backs when resting.

Before they were the lovely winged creatures you see skimming and darting through the air over the water, they were nymphs. The nymphs are the infant dragon- or damsel- flies. They are plain, usually dingy brown, and have no wings. They have six legs at the front of their bodies, looking much like a spider’s. They eat tadpoles, small fish, and insects- almost anything smaller than they are. They can live as nymphs for a few months. Some species live at this stage up to five years. The nymph may remain hidden in the rubbish at the bottom of the pond or may cling to water weeds at the sides, because different species have different habits. But in them all we find a most amazing lower lip. There are some good pictures here: http://marcheath.blogspot.com/2018/02/emperor-dragonfly-nymph-anax-imperator.html
This is so large that it covers the lower part of the face like a mask, and when folded back it 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.

METHOD The work of observing the habits of adult dragonflies should be largely done in the field during late summer and early autumn. The points for observation should be given the pupils for summer vacation use, and the results placed in the field notebook.

The nymphs may be studied in the spring, when getting material for the aquarium. April and May are good months for securing them. They are collected by using a dip net, and are found in the bottoms of reedy ponds or along the edges of slow-flowing streams. These nymphs are so voracious that they cannot be trusted in the aquarium with other insects; each must be kept by itself. They may be fed by placing other water insects in the aquarium with them or by giving them pieces of fresh meat. In the latter case, tie the meat to a thread so that it may be removed after a few hours, if not eaten, since it soon renders the water foul.

The dragonfly aquarium should have sand at the bottom and some water weeds planted in it, and there should be some object in it which extends above the sur- face of the water which the nymphs, when ready to change to adults, can climb upon while they are shedding the last nymphal skin and spreading their new wings.

Questions to discover through personal observation:
Where did you find these insects? Were they at the bottom of the pond or along the edges among the water weeds? 2. Are there any plumelike gills at the end of the body? If so, how many? Are these platelike gills used for swimming? If there are three of these, which is the longer? Do you know whether the nymphs with these long gills develop into dragon- flies or into damsel flies? 3. If there are no plumelike gills at the end of the body, how do the insects move? Can they swim? What is the general color of the body? Explain how this color protects them from observation. What ene- mies does it protect them from? 4. Are the eyes large? Can you see the little wing pads on the back in which the wings are developing? Are the antennae long? 5. Observe how the nymphs of both dragonflies and damselflies seize their prey. Describe the great lower lip when extended for prey. How does it look when folded up? 6. Can you see how a nymph without the plumelike gills breathes? Notice if the water is drawn into the rear end of the body and then expelled. Does this process help the insect in swimming? 7. When the dragonfly or damsel fly nymph has reached its full growth, where does it go to change to the winged form? How does this change take place? Look on the rushes and reeds along the pond margin, and see if you can find the empty nymph skins from which the adults emerged. Wliere is the opening in them?

ADULT DRAGONFLIES: Questions to answer through direct, personal observation: Catch a dragonfly, place it under a clear glass cup or jar, large enough to cover the insect without injuring it and see how it is fitted for life in the air. Which is the widest part of its body? Note the size of the eyes compared with the remainder of the head. Do they almost meet at the top of the head? How far do they extend down the sides of the head? Why do you think the dragonfly needs such large eyes? Why does a creature with such eyes not need long antenna? Can you see the dragonfly’s antennae? Using a magnifying glass, try to look at the little, swollen triangle between the place where the two eyes join and the forehead; can you see the little, simple eyes? Can you see the mouth-parts?

2. Next to the head, which is the widest and strongest part of the body? Why does the thorax need to be so big and strong? Study the wings. How do the hind wings differ in shape from the front wings? How is the thin membrane of the wings made strong? Are the wings spotted or colored? If so, how? Can you see if the wings are folded along the front edges? Does this give strength to the part of the wing which cuts the air? Take a piece of writing paper and see how easily it bends. Now fold the paper two or three times like a fan and try to bend it. Note how much stiffer it is. Is it this principle which strengthens the dragonfly’s wings? Why do these wings need to be strong? 3.

Is the dragonfly’s abdomen as wide as the front part of the body? What help is it to the insect when flying to have such a stong abdomen?

OUTLINE FOR FIELD NOTES Go to a pond or sluggish stream when the sun is shining, preferably at midday, and note as far as possible the following things: 1. Do you see dragonflics darting over the pond? Describe their flight. They are hunting flies and mosquitoes and other insects on the wing; note how they do it. If the sky becomes cloudy, can you see the dragonflies hunting? In looking over a pond where there are many dragonflies darting about, do the larger species fly higher than the smaller ones? 2. Note the way the dragonflies hold their wings when they are resting. Do they rest with their wings folded together over the abdomen or are they extended out at an angle to the abdomen? Do you know how this difference in attitude of resting determines one difference between the damsel flies and the dragonflies? 5. The damsel flies are those which hold their wings folded above the back when resting. Are these as large and strong- bodied as the dragonflies? Are their bodies more brilliantly colored? How does the shape of the head and eyes differ from those of the dragonflies? How many different-colored damselfles can you find? 4. Do you see some dragonflies clipping down in the water as they fly? Possibly they are laying their eggs. Note if you find any clinging to reeds or other plants with their tails below the face of the water. If so, these are likely inserting their eggs into slits they have made in the stems or leaves just below the water’s surface.

Above adapted from Comstock’s Handbook of Nature Study

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