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THE PERIODICAL CICADA. 
THE UNDERGROUND LIFE OF THE CICADA. 
EXPERIMENTAL PROOFS OF THE LONG "UNDERGROUND LIFE. 
The aerial life and habits of the periodical Cicada, which have so for 
only been discussed, are open to easy study and have been fairly well 
understood, certainly since the time of Hildreth, Potter, and Smith ; 
but from the time of the disappearance of the young larva beneath the 
soil and thereafter, throughout its long hypogean existence, observa- 
tions are difficult and have hitherto for the most part been limited to 
the occasional and accidental unearthing of specimens, and no consec- 
utive series of observations of a definite brood or generation have been 
made. The discovery of and the proof for the 17-year or 13-year 
period for the development of the Cicada is, therefore, based solely on 
chronological records, but so noteworthy are the recurrences of the 
important broods and so full and complete are the records, some broods 
having been regularly recorded on the occasion of each visit for nearly 
two hundred years, that there is no possibility of doubting the accu- 
racy of the time periods from such records alone j nevertheless, this 
unusual feature in the life of the Cicada always arouses skepticism in 
the minds of persons who have not given the matter study nor have 
examined the historical records. To silence such objectors, rather than 
because of the need of experimental proof, Professor Piley was for 
many years interested in demonstrating by actual rearing experiments 
the period of underground development of this insect; in other words, 
to follow a particular generation through its subterranean life of seven- 
teen or thirteen years, as the case might be, watching its development 
and preserving examples of the different stages. 
The great difficulty of conducting to a successful termination experi- 
ments of this sort will be appreciated when the long period over which 
the experiments must necessarily extend is remembered. The extreme 
delicacy and softness of the larva? themselves, especially in the. first 
years of their existence, introduces an additional difficulty, as the 
slightest touch or pressure injures or crushes them and renders them 
unrecognizable. It is therefore often difficult to find them, even when 
the soil is very thickly tenanted. 
The difficulty of carrying out breeding experiments with the Cicada 
under any but natural conditions is illustrated by various efforts in this 
direction undertaken by this Division. In one instance a number of 
newly hatched Cicada larvae were allowed to penetrate the soil about a 
potted oak tree of small size. ^None of these larva? survived for a 
single year. In another instance the larva? were allowed to penetrate 
the soil in large breeding tanks, each containing young trees, the tanks 
being planted out of doors in the soil. These were left undisturbed for 
a number of years, and although the conditions were seemingly very 
favorable for a successful outcome, when an examination was finally 
made, no traces of the larva? were found. 
