252 EEPOKT OF THE COMMISSIONER OF AGRICULTURE. 



ported in northeastern Alabama, and more especially those of Saint 

 Clair County (see p. 250), belong to the Brood XXII rather than to Brood 

 VIL 



The Western branch of the brood is a compact one of vast extent 

 and consisting of Indiana, the western half of Ohio, a number of coun- 

 ties in Kentucky along the Ohio River, and a narrow strip in Eastern 

 Illinois adjacent to the Indiana line. This comf>acfc area extends north- 

 ward into Michigan, but here the brood appears already to be broken 

 up into several detached areas. From Indiana only a few counties 

 have not been heard from ; the Cicadas appear to be getting less 

 numerous, and even scarce, in the northernmost counties and entirely 

 absent in a few counties in the northwestern corner of the State.* In 

 Ohio the brood extends east of the Scioto River at Columbus, but north 

 of this place a number of counties in the western half of the State ap- 

 pear not to be occupied by it. A few detached localities are reported 

 from the more central region of Illinois, and the southernmost locali- 

 ties in that State, where this brood comes in contact with Brood VII, 

 have already been referred to on p. 249. Finally a single, but very def- 

 inite, report of the appearance of the Cicada in Southern Wisconsin 

 has been received. This locality is very interesting, but widely sepa- 

 rated from the main body. 



SUMMARY OF DISTRIBUTION AND FUTURE APPEARANCE OF DIFFER- 

 ENT BROODS. 



Summing up the distribution of the Periodical Cicada (both 17 and 

 13 ;year races) within the United States, as now ascertained, it will be 

 seen that the Cicada is known to occur in all the States east of the plains, 

 excepting the northern portion of New England, northern Michigan, and 

 the whole of Minnesota. It thus appears that this Cicada does not breed 

 in those Northern States or i^ortions thereof in which the woods are com- 

 posed more or less exclusively of pine trees or other conifers, Rhode 

 Island possesses no broods, so far 'as we know, but this may be due to 

 want of proper records, as several broods reach close to the borders of 

 that State. Neither does the species occur in the peninsula of Florida, 

 for reasons either of a climatic or geologic nature. Our knowledge of 

 the western extent has greatly increased since 1S6S, and several broods 

 can now be traced as far west as eastern Montana and Wyoming, central 

 Colorado, and the extreme western parts of Texas, while less reliable evi- 

 dence even indicates that the species may occur in western Montana 

 along streams emptying into the Pacific Ocean. Unless this report be 

 substantiated in future the distribution will not extend beyond the divid- 

 ing range of the Rocky Mountains. The connection between the distri- 

 bution of this insect and the botanical, geological, and topographical 

 cbaracteristics of the country forms a very interesting subject for con- 

 sideration. 



The earlier authors on the subject of distribution of the Cicada, in- 

 cluding Prof. N. Potter, Dr. Harris, and Dr. Smith, arranged the chro- 

 nology solely according to the years of the appearance of the Cicada. Dr. 

 Fitch was the first to introduce the numbering of the different broods. 

 However, from want of sufficient data, only a few of the broods actually 

 in existence were known to him, and he confounded the broods of the 

 seventeen-year and thirteen-year races of the insect. Thus, in order to 

 avoid further conflision, we were obliged, in 1868, to renurnber the 

 broods, beginning with the brood that was to appear the year following 

 that date, and numbering consecutively the broods as they were to ap- 



• Tliis ifl just the area occupied by Brood V (1871 and 1888). 



