ORDER HEMIPTERA 



95 



tory. The most common species, or, for the Homoptera, one 

 of the most widely known, is the seventeen-year cicada, 

 which is especially remarkable on account of its long life. 

 The seventeen-year cycle is certainly known and well estab- 

 lished by observation. The adults appear at these periodical 

 intervals in the latter part of June and they are apparent 



Fig. o3.—Tibicen septendecem: adults on two-year-old apple tree. 

 (Photo from Ohio Exp. Sta.) 



during- this stage when they feed very slightly on vegetation, 

 mate and deposit their eggs during a period of four' or five 

 weeks, though they are seen in great abundance for a period 

 of only a few days. They are noticeable from their size 

 and from the very loud note that is produced by the males. 

 The song is a long-drawn-out sort of screech and is produced 



