80 THE PERLID.E 



existence i.e., it becomes a chrysalis, and finally, 

 when the chrysalis stage is over, it tears open the 

 sac covering which has protected it during the dormant 

 existence. Swimming to the surface, it either supports 

 itself against some floating object or makes its way 

 to the bank. The skin then splits open and the insect 

 enters the imago stage direct, the pupal skin being 

 generally left in the water. 



The other class of larva of the Caddis-fly makes a 

 permanent home by spinning a sac, like a bag, attaching 

 it to some sheltered spot, and covering it with stones, 

 etc. It leaves this home in search of food, and when 

 the pupal stage approaches, it partially closes the 

 aperture and undergoes a pupal phase similar to the 

 one above described, before it assumes its imago 

 existence. Some well-known forms of the Trichoptera 

 are as follows : The Red Sedge, Silver Sedge, Orange 

 Sedge, Grannom, the Welshman's Button, the Cinna- 

 mon-fly, the Sand-fly, etc. In Plate XV. will be 

 seen two exquisite drawings of the larva and the pupa 

 of the Caddis-fly by Mr. Knight, magnified about five 

 diameters. 



Fig. 1 is the larval condition of the Phryganea, one 

 of the Sedge family. 



Fig. 2 is the pupal stage of the same water insect. 



THE PERLIDJE : THE STONE-FLY 

 The sub-aqueous existence of the Perlidse after 

 leaving its egg and until maturity is reached consists 

 of a crawling and swimming larval condition lasting 



