THE PERIODICAL CICADA 



scattering colonies farther west. Brood III, 1929, is 

 mostly confined to Iowa, Illinois, and Missouri. The 

 largest of the broods is X, covering almost the entire range 

 of the seventeen-year race. This brood made its last 

 appearance in 19 19, and is due next, therefore, in 1936. 

 The series of broods as numbered thus follows the suc- 

 cessive years to Brood XVII, the last brood of the seven- 

 teen-year race, which will return next in 1943. 



The small and uncertain broods of the seventeen-year 

 race are VII, XII, XV, XVI, and XVII. The cicadas 

 that emerge in the vears corresponding with these num- 

 bers represent incipient broods, being probably the 

 descendants of a few individuals that sometime became 

 separated from the larger broods of the years preceding 

 or following. One of the smallest of the seventeen-year 

 broods is XI, but since its colonies occur in Massachu- 

 setts, Connecticut, and Rhode Island, it is likely that it 

 was more numerous in individuals in former times than 

 at present. The brood with the oldest recorded history 

 is XIV. This is a large brood extending over much of 

 the range of the seventeen-year race, with colonies in 

 eastern Massachusetts on Cape Cod and near Plymouth, 

 the emergence of which was observed bv the early settlers 

 probably in 1634. 



The broods of the thirteen-year race are numbered 

 from XVIII to XXX, Brood XVIII being that which 

 appeared last in 1919. But there are only two important 

 broods of this southern race, XIX, which emerged in 

 1920, and XXII, which emerged in 1924. In most of the 

 other years the shorter-lived race is represented by only 

 a few individuals that emerge here and there over its 

 range; and none at all are known to appear during the 

 years corresponding with the numbers XXV and XXVIII. 



The Hatching of the Eggs 



Five weeks have elapsed since the departure of the 

 cicada swarms. It is nearly six weeks since egg laying 



[2.7] 



