396 



AN INTRODUCTION TO ENTOMOLOGY 



Figure 461 represents the wings of an adult cicada. In this figure, 

 where the veins are not ntunbered their homologies are indicated by 

 the numbering of the cells behind them. In the adult wing there 

 is a massing of several veins along the costal margin of the wing, 

 and the cross-veins have the same appearance as the branches of 

 the primary veins. 



Further details regarding the development of the wings of a cicada, 

 and accounts of the development of the wings of representatives 

 of other families of the Homoptera, are given in "The Wings of 

 Insects" (Comstock '18). 



In the Homoptera the front part of the head is bent under and 

 back so that the beak arises from the hind part of the lower side of 

 the head. There is no distinct neck; and so closely is the head 

 applied to the thorax that usually the front coxse are in contact 



4r 



The wings of a cicada. 



with the sides of the head, and in many forms the beak appears to 

 arise from between the front legs. 



The mouth-parts are formed for piercing and sucking. The 

 piercing organs consist of four long, bristle-like setae, the mandibular 

 and maxillary setae; these are enclosed in a long, jointed sheath, 

 which is the labium. The labium and the enclosed setas constitute 

 what is commonly termed the beak. 



The beak, however, corresponds to only a portion of the mouth- 

 parts of a chewing insect, each mandibular and maxillary seta being 

 only a part of a mandible or maxilla; in each case another part of 

 the organ enters into the composition of the head-capsule. 



As an example of the homopterous type of head and mouth-parts 

 those of a cicada are probably the most available, on account of the 

 large size of these insects and the comparative ease with wh^ch the 



