134 INSECTS HYMENOPTERA DIAGRAM 6. 



habits. We meet with larva) 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 Phryganeae 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, 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 phryganese 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 ephemerae are remarkable for only living a day at most ; 

 but this is only true of the perfect insect. Before reaching it, 

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

 for three year. These larvae are generally found in rivers. 

 They are small, and may be recognised 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 

 ephemerae 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. 



OEDEE HYMENOPTERA. 



The order Hymenoptera includes the two insects which 



