igO ARTHROPODS : INSECTS. 



and semi-pupa states extends through two or three 

 years, and all this time they live in the water. When 



Fig- 331 — Sione Fly, half natural size. 



Fig. 332. — May Fly. 



ready for their final changes, the pupa; 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 cover- 

 ing. After this the wings are brighter, and the tails 

 longer. May Flies appear in such immense swarms 

 in some parts of Europe, that the people 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, a large head, and very large eyes. They at 

 once arrest our attention by their large size, light and 

 graceful form, variegated colors, and the great veloc- 

 ity with which they speed their way over fields and 



