132 PEKIODICAL CICADA. 



It will have been observed that in giving the above locust range I 

 have often referred to rivers as forming its boundaries. It will, of 

 course, be understood that it is not the rivers themselves, but the wood 

 which skirt their banks, which really constitutes the boundary. 



It is not to be inferred that all places within this outline were equally 

 infested by these insects. Every one who traveled through this ex- 

 tensive region during their active period must have remarked that the 

 locusts were much more abundant in some places than in others, even 

 where the supply of timber was equally abundant. I heard of several 

 curious instances of their being abundant at one end of a long grove, 

 and almost wanting at the other. 



Neither must it be understood that no locusts were seen outside of 

 this range. The locust-line is not a simple and straight one, but more 

 or less zig-zag, being necessarily much governed by the presence or 

 absence of the timber which constitutes the natural depository of the 

 nsects' eggs. Stragglers have often been seen many miles out upon 

 the prairie, having been driven, sometimes, by high winds, and pos- 

 sibly being impelled by an instinct to extend their borders. 



I may here remark, in passing, that the Northern Illinois brood of 

 locusts of 1871 meets and interlocks more or less with the Sothern Illi- 

 nois brood of 1868, which also extended further east, into the State of 

 Indiana. Champaign county, in Illinois, which lies on the dividing 

 line, seems to belong more to the southern than the northern brood, in- 

 asmuch as but few locusts were seen in this county in 1871, and these 

 mostly in the northwestern part, whilst all the southern half of the 

 county was densely infested by them in 1868. 



I take this opportunity to express my thanks to the many persons 

 who have assisted me in this enquiry, and upon whose authority 

 the above statements are made. I deem it just and proper to give the 

 names of these individuals in their geographical order. Suel Foster, 

 of Muscatine, Iowa ; Charles W. LilHe, Independence, Iowa ; J. L. 

 Budd, Cedar Rapids, Iowa; Postmaster of Lansing, in Northeastern 

 Iowa; Dr. John Conant, Prairie du Chien, Wisconsin; Morrow and 

 Brother, Madison, Wisconsin ; L. Camfield, Benton Harbor, Michigan ; 

 Judge David Turner, Crown Point, Indiana; J. B. Dodge, Warsaw, 

 Indiana; Dr. J. H. Longbridge, Rensselaer, Indiana; P. D. Hammond, 

 LiFayette, Indiana; B. N. McKinstry, Kankakee, Illinois; L. H. 

 Fairchild, Danville, Illinois; J. R. Parks, Tolono, Illinois; E. Daggy, 

 Tuscola, Illinois ; Prof. Burrill and Dr. Howard, Champaign, Illinois ; 

 Charles S. Davis, Decatur, Illinois ; Prof. J. B. Turner, Jacksonville, 



