176 ARTICULATES: INSECTS. 



MAY-FLIES, OR EPHEMERAS. 

 Though these insects live only for a few hours or a 

 day in the perfect state, their existence in the larva 

 and semi-pupa state extends through two or three years, 



Fig. 331 . — Stone-Fly, half natural size. Fig. 332. — May-Fly. 



and all this time they live in the water. When about 

 to go through their final changes, the pupae crawl to 

 the surface, cast off the pupa-skin, and appear at first 

 to be fully developed ; this is the sub-imago state ; they 

 then fly with difficulty to the shore, affix themselves to 

 plants and trees, and cast off a very delicate covering. 

 After this the wings are brighter, and the tails greatly 

 increase in length. May-Plies appear in such im- 

 mense swarms in some parts of Europe, that the peo- 

 ple collect their dead bodies into heaps to enrich the 

 land. They are common in this country. One of our 

 species is shown in Figure 332. 



DRAGON-FLIES, OR DARNING-NEEDLES. 



These insects have a long body, large, lustrous, gauze- 

 like wings, large head, and very large eyes. They at 

 once arrest our attention by their large size, light and 



