neuropTerA. 



419 



The pupa (Fig. 392) differs only from the larva (Fig. 391) in having 

 the rudiments of wings. When about to undergo their metamor- 

 phosis, they come out of the water and cling to plants, &c. The 

 skin cracks on the back when it is dry, and there comes out a heavy 

 insect, which flies feebly, and has opaque wings. It is still enveloped 

 in a very thin skin, of which a last moult, after a few^ hours, frees it. 

 This skin remains sticking to the plant on which the moulting was 

 effected, preserving the shape of the insect. This moult is peculiar 



►fit 



Fig. 391. — Larva of an Ephemera. 



Fig. 392. — Pupa of an Ephemera. 



to the EpJwjwcB ; it is the transition from the false imago (pseudo- 

 imago) to the imago. 



In the same family is the genus Cloeon, whose larvae prey on 

 minute insects. The Cloeon diptera (Fig. 393), which has only two 

 wings, is often to be met with in houses, resting on the window panes 

 and curtains. All these insects keep badly in collections ; they lose 

 their shape, and their members are so fragile that the least shock 

 suffices to break them. 



The LibellulcE^ or Dragon-Flies, are insects of a well-detined type. 



