in Illinois, the 13-year Lower Mississippi River Valley 

 Brood (Marlatt's XXIII), which emerged in Union 

 and Jackson counties in 1859. Thomas thought that 

 this brood also had a 17-year life cycle (Thomas 

 1865:458-459). 



In 1868 Benjamin Walsh and C. V. Riley raised 

 the number of Illinois broods to four, adding the 

 17-year lowan Brood (Marlatt's III). These authors 

 also suggested that another brood, Marlatt's IV. might 

 occur in Illinois, but this has not proved to be the 

 case. Further, they outlined the range of the Great 

 Southern Brood (Marlatt's XIX) in Illinois, and with 

 few exceptions the range is the same today, accord- 

 ing to my 1972 findings. 



In tlie same year, 1868, Riley reported that not 

 all broods had 17-year life cycles but that some had 

 13-year life cycles. Riley's discovery was made dur- 

 ing his study of the Great Southern Brood ( Marlatt's 

 XIX), wherein he noted an 1803 record from Alton, 

 Illinois. According to Marlatt (1907), Dr. D. L. 

 Phares of Mississippi probably was the very first, in 

 1845, to "announce the 13-year period for the south- 

 em broods," but because the article was published 

 in a newspaper witli local circulation, this notice 

 did not come to the immediate attention of entomolo- 

 gists. 



In the following year (1869) Riley published his 

 first annual report on the insects of Missouri and 

 expanded his and Walsh's previous treatment of 

 periodical cicadas by incorporating information from 

 a manuscript written by Dr. Gideon B. Smith of 

 Maryland, then deceased. (This manuscript was pub- 

 lished in its entirety by Marlatt in 1898.) From the 

 16 broods estimated to exist in the USA in 1868, 

 Riley increased the list to 22 broods, changing the 

 numbers of all broods except Brood I. Riley continued 

 his surveillance of periodical cicadas, publishing on 

 them and including Illinois records, until 1894 just 

 before his untimely death from a fall in 1895. 



By 1869, therefore, the literature referred to broods 

 numbered separately and differently bv Fitch (1856), 

 Walsh & Riley (1868), and Riley (1869). The records 

 included well-documented data as well as mere recol- 

 lections, some of which were considered questionable 

 at the time and some of which have since pro\ed 

 to be in error. 



A couple of years later in 1871, William LeBaron 

 (1872) wrote that "one of the special duties of the 

 State Entomologist of Illinois, in the season of 1871. 

 [was] to determine, as nearly as possible, the range 

 of the present brood, and to make a record of it, 

 which may be consulted by those who may take an 

 interest in this matter, seventeen years hence." His 

 detailed report of the distribution of this brood, t]ie 



Northern Illinois Brood (Marlatt's XIII). fits well 

 within the broad limits mentioned by Fitch in 1856 

 and confirmed by my own sur\ey in 1973. LeBaron 

 personally noted the absence of this brood in Mason 

 County, supposedly because of some effects of the 

 sandy soils in this count)'. However, a Mr. J. Cochrane 

 of Havana. Mason County, convinced LeBaron that 

 a brood emerged in large numliers in Mason County 

 in 1859 or 1860, which LeBaron thought might really 

 be 1861, the year when the lowan Brood (Marlatt's 

 III) emerged. This supposed emergence, inexactly 

 recalled some 10 years after its alleged occurrence, 

 does not fit with recent data and probably should 

 be discarded as questionable evidence. 



It was not until 1885. when Riley made special 

 inquin' of many persons, that the 17-year Great 

 Eastern Brood (Marlatt's X) was proved to occur in 

 Illinois at the eastern border and became the fifth 

 Illinois brood. Some scattered precocious or late 

 emergences of out-of-season broods undoubtedly were 

 included in these Illinois records, but in general, 

 Riley's limitations of the range of this brood in Illi- 

 nois are the same as those noted in recent years. .\ 

 sixth Illinois brood, mentioned by Riley in 1885. is 

 probably incorrect, according to my data. 



U.S. government entomologists L. O. Howard, 

 C. L. Marlatt. F. M. Webster. M. \'. Slingerland. and 

 others became active in the survey of the USA cicada 

 broods in the 1890's and early 1900's. .\t the Bureau 

 of Entomology, Washington. D.C.. at first under 

 Riley, Marlatt e\entually took oxer as the principal 

 compiler of the ranges of the broods. In 1907 ( re- 

 issued in 1923) Marlatt published what was then the 

 most complete and definiti\e work on the periodical 

 cicada. In it he compiled all the principal literature 

 and records for each brood, including, unfortimately. 

 the questionable records. Ho increased the number 

 of broods to 30 even though he considered some 

 doubtful. It was as if Marlatt wanted the total num- 

 ber of broods to equal the sum of the t\vo life cycles 

 (17 + 13). and to achieve this e(iualit>". he appe;ired 

 willing to include any record he could find. Further- 

 more, he renumbered the broods differently than had 

 Riley in 1869. Generally. Marlatt's nimibered desig- 

 nations have been accepted and are in use today. 

 Instead of 30 broods, .\lexander 6c Moore (1962) 

 believe that tliere may be no more than IS \alid 

 broods in the eastern USA. 



S. .\. Forbes, head of the predecessor organizations 

 of the Illinois Natiiral Histor>- Sur\oy. his stafF, 

 teachers, and others continued to gather data on the 

 Illinois broods and supply Riley. Howard. Marlatt, 

 and others with information. Most of the early 

 cicada specimens, if any were kept, are no longer in 

 tlie Sur\ey's collections. The Sur\ey has only a few 



