When its season of larva life is over, it retires to the bottom of the vessel to repose, and becomes a pupa. When the crumpled form of the gaudy fly begins to expand within, and to knock at the door of its sepulchre, the pupa quits the watery element for ever, and betakes itself to the dry land, or to the slip of cork placed in the jar for its use. There, the apparently painful process of its unfolding takes place, and the fly slowly emerges. The envelope bursts asunder, and the head of the lovely, but bloodthirsty damsel, emerges to the light. Next appear the legs, not in action, but gathered up to the breast, as if in spasm, and, for a time, the effort is suspended, and the helpless, half-formed beauty hangs back her head, as if languid with the exhaustion of pain. Once more she pants for freedom, sighing to sun herself in the blue ether, and another struggle is made. This time she clutches at the pupa case with a convulsive grasp, and drags forth the whole of her delicate body from the grave, and there remains motionless, still clinging to it, as if contemplating the baseness of her origin—for beauty is ever the offspring of the dust. She is free at last—but, ah! how helpless. Her wings are damp, and closely folded, and would not yield to the wish for flight, even were she already possessed of the power to stir them into action. She is on the threshold of a new world—a creature born of the dust, just escaped from the dust; and now as we watch her wings dry and expand, away she goes—a thing of light and loveliness soaring heavenward. Like the mortal ark, out of which the spirit of man escapes, we may, without losing sight of the disparity of the subjects, speak of the chrysalis of the dragon fly as—
"A worn-out fetter, which the soul
Has broken, and thrown away."
DRAGON FLIES.
a. Virgin Dragon Fly—Calepteryx Virgo.
b. Green Dragon Fly—Æshna varia
THE GNAT—Culex pipiens (LINNÆUS)
In the operation of dragging, many curious larva are brought out, and the mud should be searched carefully for them before washing the net for another cast. The larva of the gnat is one of the most interesting of these, and during summer may be obtained in hundreds if a little of the brook water be dipped to fill the jar with, and a few light weeds thrown in to supply oxygen. These larva are the produce of eggs deposited in a curious manner.
The gnats repair to the water soon after day-break, and commence an operation of a truly naval kind, such as would have delighted the savage heart of Peter the Great, could he have witnessed it in the midst of his dreams of achieving naval power. In fact, the mother gnats construct rafts of eggs, and each egg is added as a separate timber of the vessel, till a boat-like structure is produced. The skill as well as the necessity of the construction is well tested by the fact that each separate egg would of itself sink to the bottom, whereas being protruded one by one into the angle formed by the hind legs which serve as stocks for the future vessel, and successively glued to each other by the fluid which exudes with them, they gradually assume, under her guidance, a neat boat-like form of about three hundred minute pyramidal eggs.
"The most violent agitation," says Kirby, "cannot sink it, and what is more extraordinary, and a property still a disideratum in our life-boats, though hollow it never becomes filled with water, even though exposed."
The grubs at last come forth, and lead a very merry sort of life under the shadow of the sedges. Placed in the jars they appear at first sight like newly hatched fry of fishes, but we soon detect the segments of their pellucid bodies, and, as might be expected in water larva, they breathe at the wrong end, and hence most of their merry movements are performed between the surface and the bottom; every time they descend they carry with them a minute bubble from the surface. Under a good lens the pretty creature changes its form considerably, and comes out in the pantomime style, with huge horns, goggle eyes, and starched frills of shaggy hair; but then the tail becomes the object of attraction, and we watch the breathing action of the curious funnel which breaks away at an angle from the last segment of the body.