302 



INTRODUCTION TO ZOOLOGY 



CHAP. 



ing has not yet appeared, and the abdomen has yet to shrink 

 in width, and increase in length. 



The wings are at first soft, moist, and crumpled-looking 

 (Fig. 224), but now they begin to expand very quickly, still 

 held vertically side by side, but kept carefully apart from 

 each other, the abdomen being curved away from them, 

 so that they have all the room possible for their free expan- 



FIG. 223. Stage 2 in the last 

 moult of the Nymph of 

 Aeschna when the tip of the 

 abdomen is being with- 

 drawn from the old skin. 



w, Wings of imago not yet expanded ; 

 l.s, larval skin. 



sion. 



FIG. 224. Stage 3 in the last moult 

 of the Nymph of Aeschna. 



Abdomen just freed from larval skin. Wings 

 expanding and abdomen shrinking in width. 



In half an hour or less, the wings are fully expanded 

 (Fig. 225), but still some hours of rest are needed before 

 they are sufficiently firm and dry for flight. During this 

 time the abdomen reaches its full length, but gets thinner, 

 letting fall gradually, drop by drop, the liquid which dis- 

 tended it ; slowly also the characteristic colouring of the 

 Dragon-fly appears. Finally, perhaps three hours after the 

 imago began to withdraw itself from the larval skin, the 

 wings are for the first time spread out at right angles to 

 the body, and, after moving them once or twice, the Dragon- 

 fly sails off into the air, and begins its active predatory life, 



