THE AMERICAN ENTOMOLOGIST. 



27 



ON THE DISTRIBUTION OF THE SEVENTEEN 



TEAR CICADA OF THE BROOD OF 1878, 



OR RILEY'S BROOD XIII, IN IOWA. 



BY PROF. C. E. DES5EV, IOWA AGR. COLLEGE. 



In June 1878 I sent out ninety-eight 

 postal .cards bearing the following inqui- 

 ries, viz.: [Fig. 7-] 



peared, the persons addressed apparently 

 thought the matter of no importance, and 

 failed to send answers. 



I also made inquiry through the students 

 of the Agricultural College and received 

 from them some reliable information. I 

 have in this way obtained a mass of infor- 



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(i) Are the Seventeen Year Locusts {Ci- 

 cada septcmdecims) abundant in your 

 neighborhood this year? (2) Are 

 they doing any damage ? (3) When 

 were they known to be in your neigh- 

 borhood before this ? (4) If this is 

 not " Locust Year " with you, please 

 to state exactly when it occurred, if 

 known to you. There are probably 

 some localities in which the Seven- 

 teen Year Locusts never have ap- 

 peared, — please to note and investi- 

 gate. 

 A few days later I published the same 

 inquiries in the " College Quarterly" (a 

 paper published by the Agricultural Col- 

 lege, and having a wide circulation, being 

 in fact sent to every county in the State). 

 As a result of these inquiries I received re- 

 plies from about fifty counties. In some 

 counties where no Cicadas have ever ap- 



mation, the greater part of which is fully 

 reliable. In a few cases only is there doubt 

 as to the value of these replies. 



As fast as answers were received I marked 

 in red upon a map those counties in which 

 the Cicadas were reported as having ap- 

 peared this year : those in which they ap- 

 peared in 187 1 were marked in blue ; while 

 those in which they have never appeared 

 were marked with a large circle [O]. A copy 

 of this map accompanies this paper. 



Twenty-eight counties were reported as 

 having more or less of the Cicadas in 1878 

 and they are seen on the map to occupy 

 a large area extending from the south- 

 eastern portion of the state northwestward 

 up the Des Moines river. This area in- 

 cludes several counties from which no 

 replies have been received, but in which 



