276 Forty-second Report on the State Museum. [134] 



An Experiment with the Thirteen-year Cicada. 



The following paper was read before the Albany Institute at its 

 meeting on October 6, 1885, with a view of making record of the 

 planting of a brood of the " thirteen-year locust," at Kenwood, near 

 Albany, and of the request that observations be made of the appear- 

 ance of the winged insect at the time that its development may be 

 expected: 



" It is probably known to all the members of the Institute that not- 

 withstanding the rapidity of multiplication in the insect world — 

 very few of the species requiring more than a year for their life- 

 cycle, and many having several generations in the year — one 

 species requires seventeen years for its development from the egg 

 to the perfect insect, viz., the seventeen-year Cicada, or the Cicada 

 septendecim. That so exceptional a life-period is still doubted by many 

 is not strange, in view of the fact that the Cicadas are seen to appear 

 at shorter intervals than seventeen years — indeed, almost every year 

 witnesses their appearance in some part of the United States. But 

 this admits of easy and satisfactory explanation. There are a number 

 of distinct broods occurring within the United States — no less than 

 twenty-one are known — having each its geographical limits, some- 

 times overlapping one another, but each ever true to its seventeen- 

 year period. Within the State of New York we have five of these 

 broods, one of which made its appearance on Long Island during the 

 past summer, in immense numbers, and another will appear also on 

 Long Island in 1889. 



" Besides this seventeen-year Cicada, Prof. Riley has also discovered 

 the existence of a thirteen-year Cicada. 



" No specific differences in appearance between these two forms can 

 be detected, for which reason the latter is not accej)ted as a distinct 

 species, but is regarded only as a form or race. The thirteen-year 

 Cicada is a southern form, which, in its northern extension, does not 

 reach further than into the southern part of Illinois. We do not have 

 it in the State of New York. 



" In the possibility that this short-period southern form may, in the 

 laj)se of time, have been developed from the normal seventeen-year 

 race, as a consequence of the higher temperature of the Southern 

 States hastening its development, Prof. Riley has, the present year, 

 undertaken to test the effect of climate on the permanency of the two 

 races, by transferring them from one region to the other. He thinks 

 it possible that a southern brood brought northward might fail to 

 appear at the expiration of thirteen years, and a northern brood taken 

 south, might appear in a less time than seventeen years. 



