170 INSECTS INJURIOUS TO VEGETATION. 



have published accounts of the occurrence of these insects in the 

 Middle, Southern, and Western States, where, at regular inter- 

 vals of seventeen years, varying according to the locality, they 

 are seen even in greater abundance than in Massachusetts. The 

 following dates and places of their ascent are given in Professor 

 Potter's "Notes on the Locusta decern Septima" (Cicada sep- 

 tendecini) ; Maryland, 1749, 1766, 1783, 1800, 1817, 1834 ; 

 South Carohna and Georgia 1817, 1834 ; Middlesex County, 

 New Jersey, 1826 ; Louisiana, 1829 ; Gallipolis, Ohio, 1821, 

 and Muskingum, 1829 : western parts of Pennsylvania, 1832 ; 

 Fall-River, Massachusetts, 1834. To these may be added from 

 other sources, :^ennsylvania, 1715, 1766, 1783, 1800, 1817;* 

 Marietta, Ohio, 1795, 1812 ; Plymouth, 1633, 1804 ; Sandwich, 

 1787, 1804, 1821 ; Genesee County, New York, 1832; Mar- 

 tha's Vineyard, 1833. From information derived from various 

 sources it appears that this species is widely spread over the coun- 

 try, with the exception only of the northern parts of New Eng- 

 land ; and that it may be seen in some portion of the United 

 States almost every year ; and, although certain disturbing causes 

 may occasionally accelerate or retard the return of individuals, or 

 even of an entire swarm, in any one place, yet the lineal descen- 

 dants of one particular family or swarm will ordinarily come forth 

 only once in seventeen years, while those of other swarms may 

 appear, after equally regular intervals, in the intervening period, 

 in other places. 



The seventeen-year Cicada (Cicada septendecim of Linnaeus), 

 in the winged state, is of a black color, with transparent wings 

 and wing-covers, the thick anterior edge and larger veins of which 



Science," p. 327 ; and a pamphlet entitled "Notes on the Locusta," &c., with 

 which I have been favored by the author, Professor Nathaniel Potter, of Baltimore. 

 This last work is exclusively devoted to the history of this insect, and has aftorded 

 me much valuable iiiformation. From these various sources I have selected the 

 principal facts which follow. Mr. Collinson's " Observations on the Cicada of 

 North America," published in the "Philosophical Transactions " of London, vol. 54, 

 p. 05, with a plate, probably refer to the seventeen-year Cicada, but the insects 

 figured are not the same, and seem to be the Cicada priiinosa of Mr. Say. 



* A writer in the " United Stales Gazette " records the appearance of these in- 

 sects in great numbers in Ger^iiantown, Pennsylvania, on the 25lh of May, at four 

 successive periods. 



