THE AMERICAN ENTOMOLOGIST. 



63 



THE PERIODICAL CICADA. 



Seventeen and Thirteen Year Broods. 



Tlicrc is probably no one American insect 

 more intimately connected with the history of 

 the United States, and of which more has been 

 wiitten, than the 17-year Cicada {Cicada sep- 

 temdecim, Linn.)* It is scarcely necessary to 

 tell Americans that, as the name implies, this 

 insect generally requires 17 years to undergo 

 its transformations ; remaining, with the excep- 

 tion of about three months, the whole of this 

 time under ground. There is not a parallel case, 

 that we know of, within the whole range of 

 Natural History ; but though so much has been 

 written about tliis Cicada, yet some of the most 

 interesting facts relative to its history were un- 

 known till the present j-ear. 



We have discovered that besides the 17-yoar 

 broods, the ax^pearance of one of which was re- 

 corded as long ago as 1033, there are also 

 13-year broods; and that, though both some- 

 times 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. It so happened tliat 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 for 

 as regards these two particular broods, has not 

 taken place since the year 1017, nor will it take 

 place again till the year 2089. 



There are absolutely no perceptible specific 

 differences between the 17-ycar 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, wo 

 shall, for convenience sake, name the 13-year 

 bi'ood Cicada tredecim, in contradistinction to 

 Cicada septemdecim, the 17-year brood. 



It is not a little singular, however, tliat 



Two distinct forms 



occur in both broods — a large one and a small 

 one — the former, by far more numerous than 

 the latter. This fact has been observed in 

 past years, and was noticed the present year by 

 independent observers in different parts of the 

 country. t Indeed, it was observed by Dr. Hil- 



• Ou page 50 of our last number, we have exjilaiiied how 

 this insect is popularly but erroneously called the 17-yeivr 

 locust. 



t 1. Ml-. V. T. Chambers, iu the August number of the 

 " American Natiu-alist, " p. 332, is said to point out some 

 variation in color from those described by Dr. Fitch. 



2. Mr.S. S. Kathvon favored us with specimens of both 

 species from Lancaster county. Pa., accompanied with the 

 following: " I am justified, I think, in concluding these are 

 two distinct species. They are different in size and colora- 

 tion, produce entirely different stridnlation, do not cohabit 

 indiscriminately," etc. 



dreth, of Marietta, Ohio, as far back as 1830 

 (Vide Silliman's Journal, XVIII, p. 47). The 

 true Cicada sejitemdecim o{ Linnaeus (Fig. 57 A, 

 ventral view of male) , as described by Harris 

 and Fitch, as well as that which we have called 

 C. tredecim, will measure on an average one and a 

 half inches from the head to tip of the closed 

 wings, and almost always expands over three 

 inches. The whole underside of the abdomen 



Ccilors— (.4) black, orange niitl orange-brown; {II) black and orange. 



is more or less of a dull orange-brown color, 

 and in the male more especially, four or five of 

 the segments are edged with the same color on 

 the back. 



The other form (Fig. 58 B, ventral view of 

 male) is not, ou an average, much more than 

 two-thirds as large, and usually lacks entirely 

 the dull orange abdominal marks, though there 

 is sometimes a faint trace of them on the edge 

 of the segments beneath. This small form was 

 described in 1851, by Dr. J. C. Fisher, in the 

 Proceedings of the "Philadelphia Academy of 

 Natural Sciences," Vol. V, p]}. 272 — 3, as a new 

 species of Cicada, hitherto confounded with 

 sejjtemdecim, and was named Cicada cassinii. 

 His desci'iption was followed bj' a note from 

 Mr. John Cassin, in which he states that the two 

 forms show no disposition to associate together, 

 and produce very different cries. The fact of 

 the very great difterence in the song of the 

 males has been fully confirmed by the observa- 

 tions of our esteemed correspondent, M. C. Hill 

 of Northeast Ohio, who likewise assures us that 

 the small form is very much less numerous than 

 the large one. 



Before Ave were aware that the small black 

 form had been described as a new species, we 

 had submitted specimens of both kinds to Dr. 



3. The correspondent to the Department of Agriculture 

 (.July Rep.) from Hematite, Mo., says, "there are two 

 species, one (both male and female) about twice the size of 

 the other, and differing greatJy also in their cries and 

 actions." 



