134 INSECTS NEUROPTERA DIAGRAM 6. 



habits. We meet with larvze in ponds which 

 drag after them a case about three-quarters of an 

 inch long. When they walk about with their 

 house, they put out their head and legs, and 

 when they are alarmed, they hide in it. These 

 are Phryganese, or caddis-flies, in the larva state. 

 These cases are formed of the materials which the 



insect finds near it : perhaps small stones, or shells, 

 Larva of Phry- 

 gana in its case, or else small twigs or pieces of leaves which the 



larva cuts for itself. All these objects are joined with threads of 

 fine silk. The phryganece are always very curious objects to 

 observe in an aquarium, and they can be made to construct 

 beautiful cases by pulling a larva out of its case, and putting it 

 into a vessel with glass beads, when it will use them to construct 

 a new house, if it can find nothing more suitable. 



The Ephemera are remarkable for only living a day at most ; 

 but this is only true of the perfect insect. Before reaching its per- 

 fect state it has lived in the larva and pupa state for one, two, 

 or three years. These larvae are generally found in rivers. They 

 are small, and may be recognized by three slender filaments at the 

 end of their abdomen. They swim by jerks. At last the time for 

 their metamorphosis arrives. It is then that the ephemera lives 

 really very quickly. The pupa emerges from the water, and is 

 transformed about the period of sunset ; it flies to some distance, 

 changes its skin with the same rapidity ; lays its eggs ; and when 

 the night has become quite dark, all the ephemera which emerged 

 from the water at sunset are already dead. They consequently 

 live less than an hour in the perfect state, after having lived two 

 or three years in the larva state. 



