The Dragon Fly Observations And Field Studies
Go into the fields and study and collect the different kinds of dragon-flies and their young stages from the bottoms of ponds. How swiftly can they fly? Do they fly high in the air as well as near the water or surface of the earth? Can you see them catch other insects? Do birds catch them and eat them? Take a position along the edge of a pond and as they come flying by swing swiftly with your net and catch one. Examine it carefully. Note the strength of the long, slender wings with their lace-like network of veins. Measure the distance across the back from tip to tip of wings. Compare this with the length from tip of head to the tip of the abdomen. Examine the head with its large compound eyes and the chewing mouth parts. Note the strong thorax which is filled with muscles to operate the wings in flight. How many segments are there to the abdomen?
With the hands or with a bucket dip up a quantity of mud and trash from the bottom of a pond and pile it on the bank. As the water soaks away watch for signs of life in the mass. If you find a few small creatures, say half an inch long with large head and eyes, broad body and with six rather long legs they are probably the nymph stages of dragon-flies. Wash the mud off of them so that you can examine them carefully. With a straw probe in the mouth and you will find that the lower lip is a long elbowed structure which can be suddenly thrown out in front of it and with a pair of pincher-like prongs at the tip it can catch and hold its prey. Some forms keep their bodies covered with mud so that they can slowly creep up close to their prey.
Collect several nymphs and keep them in a jar of water and study their movements and feeding habits. Disturb one with a pencil or straw and see how it darts forward. It has a water chamber in the large intestines, including also the respiratory tracheal gills, from which the water can be suddenly squirted which throws the insect forward. The escaping stream of water forces the insect forward on the same principle as the rotating lawn sprinkler. If you collect some almost mature nymphs and keep them for a time in a vessel of water you may see them crawl out of the water, shed their skin and change to winged adults. Collect a few adults of different species for pinning in your permanent collection.
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