THE PERIODICAL CICADA
earthly form for that of a winged insect of the upper world and sunshine, though the skins ordinarily seen are those of the annual species.
The cicada undergoes a striking transformation from the young to the adult, but it does so directly and not by means of an intervening stage, or pupa. The young of an insect that transforms directly is termed a nymph by most American entomologists. The last nymphal stage is sometimes called a "pupa," but it is not properly so designated.
The life of the periodical cicada stirs our imagination as that of no other insect does. For years we do not see the creatures, and then a springtime comes when countless thousands of them issue from the earth, undergo their transformation, and swarm into the trees. Now, for several weeks, the very air seems swayed with the monotonous rhythm of their song, while the business of mating and egg-laying goes rapidly on; and soon the twigs of trees and shrubs are everywhere scarred with slits and punctures where the eggs have been inserted. In a few weeks the noisy multitude is gone, but for the rest of the season the trees bear witness to the busy throng that so briefly inhabited them by a spotting of their foliage with masses of brown and dying leaves where the punctured stems have broken in the wind. The young cicadas that hatch from the eggs later in the summer silently drop to the earth and hastily bury themselves beneath the surface. Here they live in solitude, seldom observed by creatures of the upper world, through the long period of their adolescent years, only to enjoy at the end a few brief weeks of life in the open air in the fellowship of their kind.
The Nymphs
Of the underground life of the periodical cicada we still know very little. The fullest account of the history of this species is that given by Dr. C. L. Marlatt in his
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