THE PERIODICAL CICADA 



by Dr. J. A. Lintner in his Twelfth Report on the bisects of 

 New York, published in 1897. Dr. Lintner says the 

 turrets are constructed by the nymphs with soft pellets 

 of clay or mud brought up from below and firmly pressed 

 into place, and he records an observation on a nymph 

 caught at work with a pellet of mud in its claws. We 

 mav infer, then, that the cicada's style of work as a 

 mason is only a modification of its working methods as a 

 miner, but it appears that no one has yet actually watched 

 the construction of one of the turrets. At emergence 

 time the towers are opened at the top and the insects come 

 forth as they would from an ordinary chamber beneath the 

 level of the ground. 



The Transformation 



The period of emergence for most of the cicadas of the 

 northern, or seventeen-year, race is the latter part of 

 May. The time of their appearance over large areas is 

 much more nearlv uniform than with most other insects, 

 which show a wide variation according to temperature as 

 determined bv the season, the elevation, and the latitude. 

 Nevertheless, observations in different localities show 

 that the cicada, too, is influenced by these conditions. 

 In the South, members of the thirteen-year race may 

 emerge even a month earlier, the first individuals of the 

 southernmost broods appearing in the latter part of 

 April. 



By some feeling of impending change the mature 

 nymph, waiting in its chamber, knows when the time of 

 transformation is at hand. Somehow nature regulates 

 the event so that it will happen in the evening, but, once 

 the hour has come, no time is to be lost. The nymph 

 must break out of its cell, find a suitable molting site 

 and one in accord with the traditions of its race, and there 

 fix itself by a firm grip of the tarsal claws. At the be- 

 ginning of the principal emergence period large numbers 

 of the insects come out of their chambers as early as 



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