Page:Insects - Their Ways and Means of Living.djvu/46
reverses the natural position of the wings, but brings the hind pair outside the front pair. At the next molt, the wings retain their reversed positions, but they are once more increased in size, though they still remain far short of the dimensions of the wings of an adult grasshopper. At the time of the last molt, the grasshopper takes a position with its head downward on some stem or twig, which it grasps securely with the claws of its feet. Then, when its cuticula splits, it crawls downward out of the skin. Once free, however, it reverses its position, and the wisdom of this act is seen on observing the rapidly expanding and lengthening wings, which can now hang downward and spread out freely without danger of crumpling. In a quarter of an hour the wings have enlarged from small, insignificant pads to long, thin, membranous fans that reach to the tip of the body. This rapid growth is explained by the fact that the wings are hollow sacs; their visible increase in size is a mere distention of their wrinkled walls, for they were fully formed beneath the old cuticula and lay there before the molt as little crumpled wads, which, when released by the removal of the cases that cramped them, rapidly spread out to their full dimensions. Their thin, soft walls then come together, dry, and harden, and the limp, flabby bags are converted into organs of flight.
It is important to understand the process of molting as it takes place in the grasshopper, because the processes of metamorphosis, such as those which accomplish the transformation of a caterpillar into a butterfly, differ only in degree from those that accompany the shedding of the skin between any two stages of the grasshopper's life. The principal growth of the insect is made during those resting periods preceding the molts. It is then that the various parts enlarge and make whatever alterations in shape they are to have. The old cuticula is already loosened and the changes go on beneath it, while at the same time a new cuticula is generated over the remodeled surfaces. The