Page:Insects - Their Ways and Means of Living.djvu/263

 PERIODICAI CICADA

scattering colonies farther west. Brood III, 1929, is mostly confined to lowa, Illinois, and ,iissouri. The largest of the broods is X, covering almost the entire range of the seventeen-year race. This brood made its last appearance m 1919, and is due next, therefore, in 1936. The series of broods as numbered thus follows the suc- cessive years to Brood XVI I, the last brood of the seven- teen-year race, which will return next in I943. The small and uncertain broods of the seventeen-year race are Vil, NII, 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 vears preceding or following. One of the smallest of the seventeen-vear broods is XI, but since its colonies occur in Massahu- 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-vear race, with colonies in eastern Massachusetts on Cape Cod and near Plymouth, the emergence of which was observed by the early settlers probably in I634. The broods of the thirteen-vear race are numbered flore XVIII to XXX, Brood VIII being that which appeared last in I9I 9. But there are only two important broods of this southern race, XIX, which emerged in I92O, and XXII, which emerged in 924. 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. Trie H..TCHIN¢ Or THE EGGS Five weeks have elapsed since the departure of the cicada swarms. It is nearly six weeks since egg laying [ :17]

INSECTS