INSECTS AND PLANTS 57 



actively to the needs of continuing its species, is sluggish 

 in movement, rarely taking wing, and seldom, if ever, takes 

 food. For four or five weeks the male sings his song of 

 love and courtship, and the female busies herself for a little 

 longer period, perhaps, with the placing of the eggs which 

 are to produce the subsequent generation thirteen or seven- 

 teen years later. At the close of its short aerial existence 

 the cicada falls to the ground again, perhaps within a few 

 feet of the point from which it issued, to be there dis- 

 membered and scattered about, carpeting the surface of the 

 ground with its wings and the fragments of its body. Such 

 in brief is the life round of this anomalous insect. ... If 

 we cannot satisfactorily explain the reason for the long 

 larval life of the periodical cicada or the conditions which 

 led to the origin of this peculiarity, assuming it to be 

 abnormal, we can at least see certain advantages coming 

 to the species therefrom. Among these are the protection 

 from attacks of parasitic enemies, since we can hardly 

 conceive of a parasite limited to this cicada which could 

 possibly extend its existence over an equal term of years. 

 Its occurrence, also, in overwhelming numbers at almost 

 the same moment everywhere within the range of the 

 brood prevents its being very often seriously checked on its 

 aerial existence by the attacks of birds and other vertebrate 

 enemies, which fatten on it in enormous numbers. For 

 this species this is a most important consideration, for it is 

 naturally sluggish and helpless, and seems to lack almost 

 completely the instinct of fear common to most other 

 insects, which leaves it an easy prey to insectivorous 

 animals. The almost entire absence of fear and consequent 

 effort to save itself from danger by flight or concealment is 

 apparently a consequence of the long intervals between its 

 aerial appearances." 



The clearing of woodlands and the increase of settlement 

 acts as a serious check on the insect, and the writer, whose 

 words we have already quoted at length, continues : " To 



