98 THE PERIODICAL CICADA. 
“soaked after the wet days just past.’”’ This belief is participated in 
by Doctor Lintner in his last report on this interesting subject.* It 
should not be forgotten, however, that the great mass of the insects 
emerge without making any superficial construction whatever. 
THE ACT OF TRANSFORMATION. 
The phenomenon connected with the transformation of the period- 
ical Cicada from the pupal to the adult stage is a very interesting one 
and always fills the observer with considerable wonderment. As 
remarked by Mr. Butler, when these insects emerge from the ground 
it is usually with a rush, and a lively scramble ensues for each eleva- 
tion near the point of their emergence. Trees, bushes, weeds, poles, 
stumps, fences—in fact, everything upon which they can get above the 
level of their recent homes is ascended. ‘The instinct which has 
caused them to burrow to the surface of the ground still drives them 
in the same direction upward, and they seem to make up in activity 
for their long subterranean periods and their weeks of waiting near the 
surface when the time has finally arrived for their emergence. The 
different steps undergone by the insects in transforming from the 
pupal to the adult stage have been perhaps most accurately described 
by Professor Riley, as given below.? The plate accompanying his 
description is reproduced in this bulletin as a frontispiece. 
The unanimity with which all those which rise within a certain radius of a given tree 
crawl in a bee line to the trunk of that tree is nost interesting. To witness these pupze 
in such vast numbers that one can not step on the ground without crushing several 
swarming out of their subterranean holes and scrambling over the ground, all converg- 
ing to the one central point, and then in a steady stream clambering up the trunk and 
diverging again on the branches, is an experience not readily forgotten and affording 
good food for speculation on the nature of instinct. The phenomenon is most satis- 
factorily witnessed where there is a solitary or isolated tree. 
The pupe (frontispiece, figs. 1 and 2) begin to rise as soon as the sun is hidden behind 
the horizon, and they continue until by 9 o’clock the bulk of them have risen. A few 
stragglers continue until midnight. They instinctively crawl along the horizontal 
branches after they have ascended the trunk, and fasten themselves in any position, 
but preferably in a horizontal position on the leaves and twigs of the lowermost 
branches. In about an hour after rising and settling, the skin splits down the middle 
of the thorax from the base of the clypeus to the base of the metanotum (frontispiece, 
fig. 3), and the forming Cicada begins to issue. be 
The colors of the forming Cicada area creamy white, with the exception of the reddish 
eyes, the two strongly contrasting black patches on the prothorax, a black dash on each 
of the coxze and sometimes on the front femora, and an orange tinge at the base of 
wings. 
There are five marked positions or phases in this act of evolving from the pupa shell, 
viz, the straight or extended, the hanging or head downward, the clinging or head 
upward, the flat winged, and, finally, the roof winged. In about three minutes after 
the shell splits the forming imago extends from the rent almost on the same plane with 
a Twelfth Report Insects New York, p. 283. 
b Annual Rept. Dept. of Agriculture, 1885, pp. 237, 238. 
