188 APPLIED ENTOMOLOGY 



erably behind the body. In the far South it appears early in May while 

 near its northern limits it may be as late as early June. The insects are 

 usually in evidence for 5 or 6 weeks and are particularly noticeable in and 

 near wooded areas. They suck the sap from various trees but do little 

 injury in this way. The females lay their eggs in the smaller twigs of 

 trees, shrubs and even in herbaceous plants, the oak and hickory, and in 

 the case of fruit trees the apple seeming to be preferred for this purpose, 

 though more than 75 kinds are attacked. The eggs are placed in slits 

 made in rows by the ovipositor and a twig thus punctured is liable to 

 break off either entirely or in part. The eggs hatch in 6 or 7 weeks and 

 the nymphs drop to the ground and burrow to the roots where they feed 

 until the seventeenth spring from the one when they entered the ground, 

 most of them being between six and eighteen inches below the surface. 



During the seventeenth spring the nymphs burrow upward, nearly to 

 the surface of the ground but do not usually come out until ready for the 

 final molt producing the adult. In some cases, however, upon reaching 

 the surface they construct earthen cones or chimneys sometimes six or eight 

 inches high, within which the burrow is continued. It is supposed that 

 these are constructed where the cicadas are in moist places and these 

 structures will bring the insects out above the moisture, or that a shallow 

 soil enables them to reach the surface before the normal time, or unusu- 

 ally warm conditions hasten their start, and on their arrival they are 

 not ready for their final molt. Recent work indicates that length of 

 day is a factor. Probably the last word on this subject has not yet 

 been said. 



Arrived at the surface of the ground and ready to molt for the last 

 time the nymphs crawl out of their burrows, the greater number of them 

 in the afternoon and evening, and make their way to any objects such as 

 a tree, stick or anything at hand, and on these molt for the last time and 

 become the adults which are ready for flight the next morning. 



In the course of nearly 17 years of underground feeding it is only natu- 

 ral that some finding an abundant food supply should be able to gain a 

 little time and appear during the sixteenth year as " forerunners " of the 

 main brood, and that others with scanty food should be delayed until the 

 eighteenth season. These are few in number, however. In the South 

 is a race with a 13-year life, the origin of which as related to the other 

 race is not as yet explained. 



Though a cicada's life is (except for the race just mentioned) 17 

 years, they occur in one place or another every year, showing that in 

 some way in the past these insects have diverged so that there are now 

 17 broods. Some places are so unfortunate as to have several of these 

 broods but though the cicada may appear there every 4 or 5 years, the 

 descendants of any one of these will not be found until 17 years have 

 elapsed. 



