CHAPTER V 

 THE DEVELOPMENT OF THE WINGS OF INSECTS 



. In the discussion of the tracheation of the wings of insects and of the 

 development of the wing-veins, in an earher chapter, same data have been 

 given regarding certain changes that take place in the course of the growth 

 of wings; there are, however, other features to which reference should be 

 made in this place. 



Two quite distinct methods of development of wings exist in insects; 

 by one method, the wings are developed as outward projecting appendages 

 of the body; by the other, they reach an advanced stage of development 

 within the body. The former method of development takes place with 



nymphs, the latter, with larvae. The two 

 methods will be discussed separately. 



(a) THE DEVELOPMENT OF THE WINGS 

 OF NYMPHS 



The development of the wings of insects 

 that undergo a gradual metamorphosis, or 

 paurometabolous development, and of those 

 that undergo an incomplete metamorphosis, 

 or hemimetabolous development is compara- 

 tively simple and easily observed. With 

 these insects the wings are sac-like outgrowths, 

 which appear comparatively early in the life of 

 the nymph and become larger and larger with 

 successive molts, the expanding of the wing- 

 bud taking place immediately after the molt. 



First appearance position and growth of 

 the wings of nymphs. — The sac-like folds of 

 the body-wall that develop into wings first 

 appear along a line where the suture between 

 the tergum and the pleurum later develops. 

 In most nymphs they are so directly contin- 

 uous with the tergum and become so solidly 



Fig. III. — Wings of nymphs: 

 A, of a stone-fly {Capnia); 

 B and C, of a grasshopper; 

 D, E, and F, of a dragon-fly. 

 In the four lower figures the 

 dorsal half of the body of the 

 nymph is represented as 

 spread out flat. Figures B 

 and E are from nymphs one- 

 third grown; and C and P 

 from nymphs that were three- 

 fifths grown (After C. & N.). 



chitinized with it that they have generally 

 been interpreted as out-growths from its caudo-lateral margin (Fig. iii, 

 A, B); but in the Odonata, the wings arise in an erect position upon the 

 body-wall, at mid- way the length of their respective segments (Fig. 1 1 1 , 

 D). In insects with a complete metamorphosis, the rudiments of the wings 

 are concealed until the assumption of pupal instar, as is shown later. 



(110) 



