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THE DRAGON-FLY AND ITS VICTIM
(_Macromia sp._)
Who would suspect, as one of these dragon-flies darts by him on the roadway, that every few minutes its jaws are crunching some helpless insect caught in its flight?
When I caught the dragon-fly whose picture is shown here, I held him by the wings, and, catching a fly that buzzed about the table, dropped it in his claws. Without a moment"s hesitation his mouth opened wide and closed upon the fly. I watched it disappear underneath his great upper lip and almost fancied I could hear its sh.e.l.l crack as the powerful jaws and lower lips turned it around and around in the mouth. A few seconds only, and the sucking throat had drawn out all the blood and the lips threw out a ball-like ma.s.s made up of the fly"s wings, legs and crushed body skeleton.
Then it opened again for more.
One entomologist has said that in two hours a dragon-fly will eat at least forty house flies, and Doctor Howard says that if starved for food it will eat up its own body.
No doubt these dragons of the air are to be counted as among our greatest friends, and in places in the East where life is made a burden by that humming, stinging pest, the mosquito, its presence in great numbers helps amazingly in keeping down the day-flying forms of that insect. It has gone into the Hawaiian Islands with the mosquito and has learned there to breed in the water found on the leaves of lilies growing on dry land.
Perhaps someone will find a way to domesticate this creature and make it live upon the house flies around the house. As a first step, Needham has fed the larvae on bits of meat.
Sharpe, the British authority, has observed a dragon-fly returning again and again to the same bush, and Westwood believes he saw the same individual hawking for several weeks together over the same small pond.
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DRAGON-FLY NYMPH MASKED
(_Libellulid_)
As Kellogg says, it must, indeed, be worth more than a week of study in the house to see just once the transformation of one of these mud dragons from the bottom of a pond into a beautiful dragon of the air,--a dragon-fly.
Of all the strange, weird monsters with which I have ever had to deal, this water one seems somehow weirdest. It reminds me of those sandy-colored, deep-sea fishes which, snuggling under the sand of the sea bottom, wait for their prey to come along and then dart out and seize them with their powerful jaws.
The mud dragon has a mask which, for the purpose, is certainly the most effective thing one can imagine. Its victims must be greatly surprised to see the mask drop, revealing a sheep-like nose, mouth, and lips, while the mask itself opening out and splitting down the middle, becomes a pair of needle-margined, powerful claws so strong that even fishes are sometimes caught and held by them.
It is strange to think of this dragon concealing its claws by making a shield of them to cover its ugly face while it waits in ambush for its game.
Its eyes and body are the color of mud and must be very hard to see.
This photograph shows the mask in place, the grinning mouth a long curved slit across the face, while resting on the ground, as one would rest one"s elbow on the table, is the powerful claw arm, so strong that you would find it difficult to pull the mask away, or having done so to keep it down.
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DRAGON-FLY NYMPH UNMASKED
(_Libellulid_)
Pulled down from the mud dragon"s sheep-nosed face, the mask is resting on the ground. It can be stretched out much further and also opened up to form a pair of powerful claws. Along the edge of the mask is a fringe of inward-pointing spines like those which edge the leaf margins of a venus flytrap. The eyes are large and many-faceted and form the blunt-pointed corners of its head.
The under-water battles in which these mud dragons, or dragon-fly nymphs, take part must be something terrible. It is recorded that in Hungary 50,000 young fishes were put into a pond in which enormous numbers of these nymphs occurred and only fifty-four fishes survived. One is not surprised to learn, too, that they will eat each other up.
On the whole, however, it is doubtful if between the flies and other injurious insects which the dragon-flies destroy in the air, and those larvae of mosquitos which the water nymphs destroy in the ponds, there is any other family of insects toward which man should feel more indebted than toward the family of the odontata or dragon-flies.
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AN ABANDONED DRAGON CASE
(_Libellulid_)
From this muddy outworn sh.e.l.l, left to decay at the bottom of a pool, there came, sometime last summer, a gorgeous, four-winged dragon-fly. A little after dawn, what was once this water nymph or mud dragon, tired perhaps of its mud existence, ready anyway for the transformation, crawled up out of the water upon some stone or stick and waited there for its back to split open up and down. It pulled its soft, boneless legs from their cases, now lying along the abandoned sh.e.l.l, its wings closely packed together from the two cases on its back and its head and jaws from out the broken head sh.e.l.l. Even every air pa.s.sage running through its body shed its parchment lining.
Soft and helpless it crawled away into the gra.s.s to wait until its wet, soft outer skeleton should harden and make it possible for the powerful wing muscles to pull against it and for the broad wing films to dry and straighten out. By noon the transformation was doubtless quite complete, and flitting across the pond went the recent inhabitant of this dragon-fly case.
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THE DAMSEL FLY
(_Agrion maculatum_, Beauvois)
Most insects" legs are made to walk with, but those of the dragon-fly are not. They are bunched together so near the head that when the creature alights it can do little more than cling to what it lights upon. Instead, the legs, with their spines, form a perfect basket, open towards the front, and thus become the organs with which flies are caught.
This damsel fly, as it is called, is smaller and more delicate than the dragon-fly with quite a different head. It inhabits shrubby woodland and is not often seen. Some of its tropical relatives are creatures of extraordinary fragility and delicacy.
Its wings, which move in perfect unison, although distinct, are operated by such ingenious mechanical devices within the body as to have long ago suggested a flying machine, and it is strange how like a dragon-fly Professor Langley"s aerodrome, the first of them all, does look, although of course the aerodrome"s wings were rigid.
One realizes what enormous eyes these dragon-flies have when one begins to compare them with the size of the head.
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THE LACE-WINGED FLY AND THE APHIS LION
(_Chrysopa sp._)
So fragile and delicate does this creature appear that one can but wonder how it exists in the jungle of the gra.s.s. It has a disagreeable odor, it is said, and this is perhaps the reason that it holds its own, for it flies so slowly and is so conspicuous that it would otherwise fall a prey to every insectivorous bird and dragon-fly.
Its other self is the Aphis Lion, a wingless but very active creature which hunts for plant lice and when it finds one punctures it with its mandibles, raises it in the air and lets the blood trickle down into its mouth. It sucks eggs, too, and, shameless creature that it is, it sucks those of its own species, or would, at least, if the mother instinct had not taught the winged females to lay their eggs on the ends of long, slender, stiff stems which the undiscriminating larvae cannot climb, much as a human mother puts the pot of jam on the top shelf where the children cannot get it.
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THE WINGED ANT LION
(_Myrmeleon immaculatus_, De G.)
As with many of these monsters, it is the other self, the larva of the winged ant lion, which is the fascinating study.
This winged form merely lays the egg from which hatches out the soft, spindle-shaped young with jaws like pincers. This little creature at once marks out a tiny circle in some dry, sandy place, and begins to dig a pitfall for its prey, the ants.