THE SEVENTEEN YEAR LOCUST GROUP 



By .John A. (irnsshicl: 



RECENTLY there has been instaUcd in the insect hall a new <,n'oup 

 illustrative of the l)i()l<)<;y of the se\'enteen-year locust or periodical 

 cicada (Cicada scpicndrciiii L.), the studies having heen made in the 

 early summer of 1911 when the insects appeared in such swarms in the 

 vicinity of New York City. 



The hmg life of the cicada, ])oth as a larva and sul)se(|ucntly as a pupa, 

 is passed in the earth at some distance beneath the surface where it feeds 

 in both these stages on fluid food. In a "locust year," by which is meant 

 the year in which the insects appear above ground, the active pupa, which 

 stage is assumed six or se\'en years prior to appearance above ground, 

 makes its way toward the surface and there awaits the ad\'ent of summer 

 before breaking through the upper crust into sunshine and the outer air. 

 When the latter part of May or the first part of June arri\es, the uncouth 

 creature emerges. At the same time incredible numbers of other pupiie 

 have also emerged and attaching themselves to some surface, preferably 

 to the trunk of a tree or 

 to the undersides of 

 leaves of shrubs, they 

 shed the pupal skin and 

 appear as winged cicadas. 

 Egg-laying begins in 

 a few da\'s after the 

 emergence of the adults, 

 and it is this process 

 which results in the only 

 injury caused by them. 

 They select the slender 

 terminal twigs of a great 

 variety of orchard, shade 

 and forest trees, for the 

 purpose of depositing the 

 eggs. Deep ])unctur(> 

 are made m the twig, 

 one inunediately above 

 the other, and in each 

 puncture from twel\e to 

 twenty eggs are laid. 



These hatch toward the From ihc scxt'mccii-.vfai- loc-ust or cicada group. The 



1 ;, if cicada iiui)a ctncrfics IVom Ihc jrniuii.i and ascends some 



latter part of .sunnncr ,,,,.,,„„„„„,,,, j, „u,-s,s the outer hom.v skin and crawls 



and the little iiTul)-like out an aduH 



IS? 



