THE STUDY OF ENTOMOLOGY 217 



perfect insect is fully developed the last change to 

 the fly is effected. The first form of an insect having 

 complete metamorphosis on emerging from the egg 

 is called larva, the second pupa, and the third or 

 complete insect imago. Those of my readers who, 

 as boys, have kept and bred silkworms, will appre- 

 ciate these terms by remembering that the silkworm 

 is a larva, the chrysalis a pupa, and the moth an 

 imago. 



The nymphs of the Ephemeridse when full-grown 



rise to the surface, and winged 

 Subimago. flies emerge, leaving the shuck 



or outer skin from which they 

 have disentangled themselves on the surface. They 

 can fly, but are not the perfect insects, being covered 

 by a thin, hairy integument, which is shed at the last 

 stage. Before sheddi agL^ this hairy integument the 

 winged insect is called a dun or s ubimago . and after 

 ■■ shedding it the perfect insect is styled a spinner or 

 imago. 



The dry-fly man who wishes to identify the winged 



insects floating down or the 

 Collecting implements, immature forms in the water 



below the surface should pro- 

 vide himself with three nets, (i) An ordinary butter- 

 fly-net with short handle ; (2) a small net like a land- 

 ing-net on a diminutive scale on a ring of, say, three 

 inches in diameter ; and (3) a net for digging up 

 larvae, nymphs, etc., from the weeds or mud on the 

 bed of the river. The butterfly-net is useful to collect 



