THE STATE ENTOMOLOGIST. 19 



same insect has appeared in some part or other of the United States 

 at regular intervals of 17 years, for centuries, aye! for ages in the past. 

 Long ere Columbus trod on American soil this lowly insect must have 

 appeared regularly at its appointed time. It must have filled the 

 woods with its rattling song, when none but wild beasts and savages 

 were present to hear it. To me there is something beautiful in the 

 idea that through its periodicity we are enabled with tolerable cer- 

 tainty to go back in thought, for centuries in the past, to a particular 

 month ol a particular year, when the woods resounded with its song 

 in the same manner as they did last summer ; for so regularly do the 

 different broods appear, that one is perfectly warranted in the assump- 

 tion, that in the month of June, in the year 1738, for instance, 130 

 years ago — they appeared in the southern part of Missouri, and that 

 6 years previously they had appeared in the northwestern corner of 

 the same State. 



Though so much had hitherto been written about this Cicada, yet 

 some of the most interesting facts with regard to it were unknown till 

 the past season. A very complete article on the subject was published 

 in the December number of the American Entomologist, which I shall 

 for the most part repeat, and render more complete by the addition 

 of some facts as to their distribution, which were contained in some 

 unpublished manuscript of the late Dr. Gideon B. Smith, of Balti- 

 more, Md., and which were comunnicated to me through the kindness 

 of Dr. J. (i. Morris of the same city. 



It was my good fortune to discover that besides the 17-year broods, 

 the appearance of one of which was recorded as long ago as 1633, 

 there are also 13-year broods ;* and that, though both sometimes occur 

 in the same States, yet, in general terms, the 17-year broods may be 

 said to belong to the Northern, and the 13-year broods to the Southern 

 States, the dividing line being about latitude 38°, though in some 

 places the 17-year brood extends below this line, while in Illinois the 

 13-year brood runs up considerably beyond it. It was also exceeding- 

 ly gratifying to find, four months after I had published this fact, that 

 the same discovery had been made years before by Dr. Smith, though 

 it had never been given to the world. 



It so happened that one of the largest 17-year broods, together 

 with one of the largest 13-year broods, appeared simultaneously in 

 the summer of 1868. Such an event, so far as regards these two par- 

 ticular broods, has not taken place since the year 1647, nor will it take 

 place again till the year 2089. 



There are absolutely no perceptible specific differences between 

 the 17-year and the 13-year broods, other than in the time of maturing ; 

 but whether or not, scientifically speaking, they are to be considered 

 as specifically distinct, the 13-year brood may, for convenience sake, 

 be called Cicada tred&oim t in contradistinction to Cicada septemdecim, 



* See Journal of Agriculture, St. Louis, June 13, IS68, in which appeared the first account 

 ever published of such a brood. 



