A Child of an Hour.
Fold after fold of the wings shakes out; ring after ring of the body stretches to its proper length; the joints of the legs come to their right shape and firmness. From all the body of the insect a mist seems to pass away; and the colors of the fly come out, and red, blue, green, gold, shine in beauty.
Now let us look closely at these fine wide wings. Although they are so thin, like gauze, yet they are double. There is a surface on each side, spread over a very fine frame. The parts of this frame are small as the finest hairs.
And yet, though so tiny, they are all hollow. They are tubes or pipes. They carry through the wing, air and a very thin white fluid, which is the blood of the insect.
Now that you know this, can you clearly see how the wings expand? As soon as the dragon-fly is born from its pupa-case, air and this thin fluid are driven through these fine tubes. As they fill, they stretch out, and the thin surface which covers them spreads with them.
If you notice the fly as it is thus getting its shape, you will see that quiver which I spoke of. That motion is the pumping of air and fluid through its tubes; and, no doubt, by this action the fly spreads out its wings and its body. By such a motion the blow-fly spreads out its big head.
The dragon-fly spends about fifteen minutes in getting into shape. Sometimes half an hour is needed. After that, the fly rests for an hour or two, before it tries its wings in the air. Very likely it wishes to give its wings time to get quite firm and hard.
Butterflies, Lace-Wings, May-Flies, and other insects of the kind have their wings made in this way; so what you learn about one will help you to understand the others. You read of the Lace-Wing in the last lesson, and in the next book you will hear about Butterflies.
The May-Flies are very pretty insects. They are something like dragon-flies, but very much smaller, and not fond of tearing up other insects. You will find them in moist places. The body of the May-Fly is much slimmer even than that of the dragon-fly. The wings are unequal. Their heads are smaller. May-Flies have two fore legs, nearly as long as the body, held almost straight out as they fly. On their tails they have three long stiff hairs, twice as long as the body. These hairs spread out, fan-shape.