INSECTS
Bulletin, The Periodical Cicada, published by the United States Bureau of Entomology in 1907 . Doctor Marlatt describes six immature stages of the periodical cicada between the egg and the adult.
The young cicada that first enters the ground is a minute, soft-bodied, pale-skinned creature about a twelfth of an inch in length (Fig. 126). The body is cylindrical and is supported on two pairs of legs, the front legs being the digging organs; the somewhat elongate head bears a pair of small dark eyes and two slender, jointed antennae. At no stage has the cicada jaws like those of the grasshopper; it is a sucking insect, related to the aphids, and is provided with a beak arising from the under surface of the head, but when not in use the beak is turned backward between the bases of the front legs. Throughout the period of its underground life, the cicada subsists on the sap of roots.
Fig. 113. Nymph of the periodical cicada in the first stage, about 18 months old, enlarged 15 times. (From Marlatt)
During more than a year the young cicada retains approximately the form it has at hatching, though the body changes somewhat in shape, principally by an increase in the size of the abdomen (Fig. 113). According to Doctor Marlatt, a nymph of the seventeen-year race first sheds its skin, or molts, sometime during the first two or three months of the second year of its life.
In its second stage it becomes a little larger and is marked by a change in the structure of the front legs, the terminal foot part of each being reduced to a mere spur and the fourth section being developed into a strong, sharp-pointed pick which forms a more efficient organ for digging. The second stage lasts nearly two years; then the creature molts again and enters its third
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