114 THE PERIODICAL CICADA. 
three or four years, leaviii«z: in this i:5-year brood three or four years 
more for the j)U])al stages. 
A much more careful series of experiments was instituted in con- 
nection with the 17-year Brood X, beginning witli its last appearance 
in 1885. At the time tliat the eggs of the 13-3'ear Brood XXlll were 
being distributed to various points in the North, in order to determine 
the effect of the temperature and climate (see pp. 18-20), quantities 
of egg-laden twigs of the 17-year brood noted, collected in Virginia, 
were distributed under certain linden and oak trees on the grounds 
of the Department of Agriculture at Washington, D. C. Larv?p 
came from these twigs in some numbers and went into the soil under 
the trees, but not in such abundance as could have been wished for 
the successful outcome of the experiment. This brood was followed 
in its underground life from 1885 to 1896, at which time the speci- 
mens had become so rare that extensive digging resulted in the dis- 
covery of A^ery fev\' individuals, and further search was abandoned. 
With this ])rood the first molt occurred after one year, the second 
molt two years later, the third molt three or four years later, and the 
fourth molt after an additional three or four years, thus occupymg 
upward of ten 3"ears with the four larval changes and bringing the 
insect into the last larval stage with some six or seven 3'ears for the 
subsequent larval and pupal life. If any adults emerged at the end 
of the 17-year period in 1902 they were not observed. 
A SUCCESSFUL SEVENTEEN-YEAR BREEDING RECORD. ° 
A much more promising experiment, because of more abun(U\nt 
material, was instituted on the Department grounds in 1889 with the 
17-year race which appeared in that yeaT and which had its return 
appearance during May and June of last summer (1906). This brood 
is practical^ unrepresented m the District of Columbia, and did not 
occur at all on the Department grounds. A ver}' large quantity of 
egg-infested twigs was obtained from North Carolina, Long Island, 
Kentuck}^, and Ohio, several cartloads altogether, and were distrib- 
uted under oak and other trees on the grounds of tlie Department of 
Agriculture. The eggs in most instances were hatchmg wlien received 
and were placed under the trees in the ver}'^ best condition for the 
larva? to enter the soil, and many thousands, probably hundreds of 
thousands, of larvae actually went into the soil under these trees. This 
experiment was made during the first year of the writer's connection 
with the Bureau of Entomology, and the later examinations were 
made cliiefly under his direction. Three years after the planting the 
soil uiuU^r the trees where the egg-bearing twigs had been distributed 
« The records of the plantings on the Department grounds of the eggs of Brood X 
in 1885 and Brood XIV in 1889 are given in Appendix B, of Bui. 14. 
