PARTS OF AN INSECT. 67 



palpi ; and a lower lip, called the Idbium, which represents 

 still another pair of jaws joined together; to this joined 

 piece, or labium, are attached a pair of jointed feelers, called 

 labial palpi. In Fig. 68 these parts are shown separated 

 from the head. 



The numberless varieties of mouth-parts, peculiar to dif- 

 ferent insects, are in reality made up by modifications of the 

 parts above described. Thus, in one group of insects, the 

 mandibles are lengthened out into a piercing-like sting, while 

 some of the other parts are reduced in size, or become al- 

 most obsolete. In another group the maxillae are greatly 

 elongated, with their edges joined to form a tube, while the 

 other parts of the mouth are scarcely to be discerned. In 

 another group the labium is greatly lengthened to form a 

 tongue-like organ for lapping up food, while the mandibles 

 so big and hard in some insects are barely perceptible, 

 and of no use to the insect. 



Not only, then, do these parts assume different propor- 

 tions and different shapes in the different groups of insects, 

 but they also vary greatly in being very hard or very 

 soft. 



If the pupils will examine the different kinds of insects', 

 wings, taking the front-pair of wings for example, they will 

 find a marked difference between them, some being very 

 large and transparent, as in the dragon-fly, others being hard 

 and opaque, as in the front wings or elytra of a beetle. 

 Compare the broad and brilliant-colored wing of the butter- 

 fly with the straight and narrow fore-wing of a common 



