THE AlVIERICAN ENTOMOLOCxIST. 



63 



THE PERIODICAL CICADA. 



Seventeen and Thirteen Year liroods. 

 There is probubly no cue American insect 

 more intimatcl)- connected with the liistory of 

 the United States, and of whicli more has been 

 written, than the 17-year Cicada (Cicada sep- 

 temdccim, Linn.)* It is scarcely necessary to 

 tell ^Vmericaus 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 year. 



We have discovered that besides the 17-year 

 broods, the appearance of one of which was re- 

 corded as long ago as 1633, there are also 

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

 times occur iu 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 that one of the 

 largest 17-year broods, together with one of the 

 largest 13-year broods, appeared simultaneously 

 iu the summer of 1868. Such an event, so far 

 as regards these two particular broods, has not 

 taken place since the }'ear 1617, nor will it take 

 place again till the year 2080. 



There are absolutely no perceptible specific 

 diflerences between the 17-year and the 13-year 

 broods, other than in the time of maturing ; but 

 whether or not, scientifically speaking, they arc 

 to be considered as specifically distinct, we 

 shall, for convenience sake, name the 13-year 

 brood Cicada tredecim, iu contradistinction to 

 Cicada septemdecim, the 17-year brood. 



It is not a little singular, however, that 



Two distinct forms 



occur iu both broods — a large one and a small 

 one — the former, by fir more numerous than 

 the latter. This fact has been observed in 

 past years, and was noticed the present year by 

 independent obsei-vers in different parts of the 

 country .f Indeed, it was observed b}- Dr. Hil- 



• On page 30 of our last numbex-, we have explained how 

 this insect is popularly but erroneously oallecl the li-year 

 locust. 



t 1. Mr. V. T. Cliamljers, iu the Auirii-t numljer of the 



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

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

 true Cicada septemdecim of Linna;us (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 



Culors— (.1) black, orange and orange-brown; {B) black and orange. 



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

 and in the male more especially, four or five ■ 

 the segments are edged with the same color n, 

 the back. 



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

 male) is not, on an average, much more tha 

 two-thirds as large, and usually lacks eutirel . 

 the dull orauge abdominal marks, though the 

 is sometimes a fixint trace of them on the ed^ 

 of the segments beneath. This small form w- 

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

 Procecdiugs of the "Philadelphia Academy 

 Natural Sciences," Vol. V, pp. 272 — 3, as a nr 

 species of Cicada, hitherto confounded w 

 septemdecim, and was named Cicada cassin 

 His description was followed by a note froi 

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

 forms show no disposition to associate togethe 

 and produce very diflereut cries. The fact 

 the very great diflerencc in the song of tl 

 males has been fully confirmed by the obseiT 

 tions of our esteemed correspondeut, M. C. Hi 

 of Northeast Ohio, who likewise assures us tha 

 the small form is very much less numerous thai 

 the large one. 



Before we were aware that the small black 

 form had been described as a new species, we 

 had submitted specimens of both kinds to I.. 



3. The correspondent to the Department of Agricu} 

 (.July Kep.) from Hematite, Mo., says, "there are t>v<i 

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

 the other, and differing gi'eatly also in their cries and 



