PROOFS OF L(>Na T^NI)KK(;HorNn 1,1 KK. 113 
the life of tlic Cicada always arouscvs skcplici^m in t he iiiiiicU (.f ixM-mis 
who have not t^ivcn th(^ niatt(M- study and liaNc uol cxainiiKMl ihc 
historical records. To >il(Micc such ohjcctors, latlici- than liccjiu-c of 
the need of experiiiHMital ])roof, Profess«)r Ivilcx was for nian\ xcais 
interested in d(Mnonstr'a(iui: \)\ actual I'cai'iiiLr cxpciinicuts the period 
of underiri'ouud (h^Nc^lopnuMit of this ins(>ct ; in other \\(>i-(fs. to follow 
a ])articular t2:enera(ion through its suhteri-ancaii hfe of sexcnteeii or 
thirteen years, as tlie case niis^ht 1)(\ watchini^ it> dc\-e]o|)iiienl and 
preserviui!: cxanipk^s {)( the dill'er(Mit sta<i;es. 
The great difliculty o( conductin*; to a successful terniinat ion experi- 
ments of this sort will he a})preciated when the louir period oxer w hich 
the experiments must necessarily extend is reniemhei-ed. The ext reine 
dehcacy and softness of the larva? tlieniselves, especially in the lir-t 
years of their existence, introduces an additional difliculty, as the 
slightest touch or j)ressure injures or crushes tluun and rendcis thcin 
unrecognizahle. It is therefore often difhcult to find them. c\(mi when 
th(* soil is v(My thickly tenanted. 
The diflicult}- of carrying out hrecding ex|)erinients with the Cicada 
under any hut natural conditions is illustrated ])y various efforts in t his 
direction undertaken hy this Bureau. In one instance a niunher of 
newly hatched Cicada larvse were allow^ed to penetrate the soil about a 
j^otted oak tree of small size. Xone of these larvae survived for a 
single year. In another instance the hirvae were allowed to penetrate 
the soil in large breeding tanks, each containing young trees, the tanks 
being })lanted out of doors in the soil. These were left iuidistur1)ed for 
a number of years, and although the conditions were seemingly very 
favorable for a successful outcome, when an examination was Ihially 
made, no traces of the larv» were found. 
The earliest systematic attempts to follow tlie (lcvel()|)nicnl of the 
Cicada were mack' in the field in Missouri ])\' Professor Ivilcy. and 
subseciuently continued under the hitter's direction ])y ^Ir. J. Ci. Bar- 
low, an agent of the Bui'cau. They consisted i]i making diggings 
from year to year under trees which were known to ha\"c been thickly 
stocked with eggs. The first records aj)pr()aching hi any wav to 
comj)leteness were obtained with the l.J-year J>rood XIX, beginning 
with its appearance in issl. ()l)ser\ at ions on thi> hrood w(>r(> con- 
tinued by Mr. Barlow at Cadet, Mo., with a fair degree of rcgulaiity 
until July, 1891, when they imfortunately t(M-inimit(Ml. 
During the ten years over which these ohsei-\ at ions (>xt ended the 
msect had developed through all four larval stages and was ready to 
enter the first pupal stage. The first molt occurred after a period of 
from one year to eighteen months, the second molt after an addi- 
tional period of two years, the third molt after an additional j)eriod 
of three years, and the fourth molt after an additiojial ])eriod of 
31117— No. 71—07 8 
