PERIODICAL CICADA
The external phase of transformation, more strictly the shedding of the last nymphal skin, has been many times observed. It is nothing more than what all insects do. But the cicada is notorious because it does the thing in such a spectacular way, almost courting publicity where most insects are shy and retiring. As a conse- quence the cicada is famous; the others are known only to prying entomologists. Let us suppose now that our crawling nymph has reached a place that suits it, say on the trunk of a tree, or better still on a piece of branch provided for it and taken into a lighted room where its doings can be more clearly observed. Though the insects choose the evening for emergence, they are not bashful at all about changing their clothes in the glare of artificial light. The progress of this performance is illustrated by Figure I i8. The first drawing shows the nymph stiil creeping upward; but in the next (2) it has come to rest and is cleaning its t?ront feet and claws on the brushes of its face, just as did those confined to the glass tubes to give a demon- stration of their digging methods. The front feet done, the hind ones are next attended to. First one and then the other is slowly flexed and then straightened back- ward (3) while the foot scrapes over the side of the ab- domen. Several times these acts are repeated calmly and deliberately, for it is an important thing that the claws be well freed from any particles of dry earth that might impair their grip on the support. /?t last the toilet is completed, though the naiddle feet are always neglected, and the insect feels about on the twig, grasp- ing now here, now there, till its claws take a firm hold on the bark. At the same time it sways the body gently frona side to side as if trying to settle comfortably for the next act. Thirtv-five minutes may be consumed in the above preliminaries and there is "next a ten-minute interval of quietude before the real show begins. Then suddenly
I951
INSECTS
Ç
