THE EVIDENCE FROM THE LIFE-HISTORIES OF INSECTS. 265 



associate with it the existence of a pupa state ; but the case of the 

 Orthoptera (cricket, Fig. 176, or grasshoppers, Fig. 175, &c.) is 

 sufficient proof that the development of wings is perfectly compatible 

 with permanent activity ; the necessity for prolonged rest is in reality 

 much more intimately connected with the change in the constitution 

 of the mouth, although in many cases, no doubt, this is accompanied 

 by changes in the legs and in the internal organisation." The same 

 authority expresses the 

 opinion that, whilst the 

 biting mouth can be modi- 

 fied to form the suctorial- 

 a change witnessed in every 

 developing moth and but- 

 terfly the originally biting 

 mouth of the beetle could 

 not have been directly 

 modified, contrariwise, to 

 form a sucking apparatus, 

 "because the intermediate 

 stages would necessarily be 

 injurious." More probable 

 is it that both types have 



sprung from some more primary form of mouth, which, partaking of 

 the character of neither, has been therefore capable of modification 

 in either direction, "by gradual change, without loss of utility." 

 That such a form of mouth, united to a body of equally convenient 



FIG. 177. PLANT LICE. 

 a, wingless insect ; b, wingless insect. 



FIG. 178. RED ANTS. 

 a, male, and b, female (both winged); c, neuter. 



primitiveness, is to be found still represented in the ranks of living 

 insects, we shall shortly discover. Meanwhile the question of wings 

 awaits a brief notice. 



The nature of an insect's wing, discussed in reply to the question 

 " What is it ? " throws some light on the question of its origin. The 



