OTHER MEMBERS OF THE CLASS — INSECTA 177 



the wjuash bug (Fig. 117). There are seven or eight gener- 

 atioiLs of this bug during a season in tlie South. 



The cicadas. — The seventeen-\'ear eicada, iuij^roperly 

 called locust, lays its eggs hi slits made in twigs. The 

 young hatcli in about six weeks and enter the ground, 

 where tliey li\'e on the soil humus and sap of the tree 

 roots for nearly seventeen years. In tlie s])ring of the 



I'll., 118. — Se\entet'n-5ear ticiula. 



seventeenth year, the n>'mphs come out of the ground, 

 crawl up the trunk of the tree, where the skin bursts open 

 on the back, and the adults (Fig. 118) rnill themselves out, 

 leaving the empty nymph skins clinging to the tree. In 

 the South these cicadas live thirteen \-ears in the earth. 

 The dog-day harvest fly (Fig. ll'.l) is the in.<ect respon.sible 

 for the high, shai-p trilling that comes to us in the hot 

 summer days from the trei's where the singer lies hidden. 

 It takes this cicada onl\- two years to develop, and, since 

 there are two broods, the adults a[ipear e\'ei-y year. 



That large grou|) of insects known as the sc;de insects 

 belongs to the same order- as the lings and cicadas. These 

 are small, louselikc insects which, in many cases but not all, 

 secrete a hard, waxy covering, or scale, over the body 



HEKKIClv's /.(K)L — 12 



