422 THE INSECT WOELD. 



case of the Ephemerae do the duty of fins. The pupa already 

 presents stumps of wings. To effect its metamorphosis it drags 

 itself out of the water, where it has lived for nearly a year, 

 climbs slowly to some neighbouring plant, and hangs itself 

 there. Very soon the sun dries and hardens its skin, which 

 all of a sudden becomes bright, and cracks. The dragon-fly then 

 sets free its head and its thorax, and its legs, its wings, still soft and 

 wanting in vigour, gain strength by coming in contact with the 

 air, and, after a few hours, they have attained their full develop- 

 ment. Immediately the insect abandons, like a worn-out suit, the 

 dull slimy skin which had covered it so long, and which still pre- 

 serves its shape (Fig. 393), and dashes off in quest of prey. 



Fig. 394 Libel lula depressa, the Common Dragon-fly. 



The Libellulas are common all over the world. Their type is 

 the Libellula depressa (Fig. 394), very common in Europe. The 

 male is brown, with the abdomen blue underneath ; the female, of 

 a sort of olive-yellow, bordered by yellow on the sides. Both 

 have the abdomen broad and flattened. 



The ^Eskna, with a cylindrical abdomen, attains to the length 

 of two and a half inches. Its flight is more rapid than that of the 

 swallow. The Calepteryx flies more slowly. The male is of a 

 metallic blue, its diaphanous wings are traversed by a band of 

 greenish blue ; the female, of a bronzed green, has wings of a 

 metallic green, with a yellowish mark on the edge. These insects 

 rest on reeds, retaining their wings in a vertical position. 



