MAY-FLY FISHING. 357 



flutters before the wind in a heavy laboured flight to the shore, 

 unless in the meantime it has fallen a prey to one of its many 

 enemies among the fish or the birds. 



The above is the natural order of the metamorphosis under 

 normal circumstances, but very frequently the exact sequence 

 is destroyed by some slight accident or mishap. Thus, as an 

 example, some nymphs will reach the surface too soon, and 

 float many yards down before the splitting open of the larval 

 envelope can be accomplished ; others, again, will have par- 

 tially or even entirely emerged from the shuck before reaching 

 the top of the water, and may possibly be drowned or fatally 

 crippled in the wings. Again, in many ways the order in 

 which the various organs will become detached from the 

 exuvium can be altered : the wings may 

 be drawn out of the covers before the 

 abdomen and setae leave the larval skin, 

 or possibly one or more legs on one side 

 may get entangled, to extricate which a very 

 decided effort may be required. 



Such organs as are only of use in the 

 mud or the water are shed with the 

 exuvium ; among these may be noted 

 the mandibles, the powerful digging claws, 

 and the branchiae, whose function it is to separate from the 

 water the air required by the nymph for respiratory purposes. 

 The hairs which fringe the antennae, legs, body, and setae of 

 the nymph are absent from the winged insect, the antenna 

 are much shortened, and the mouth organs are generally atro- 

 phied. The setae of the subimago are somewhat longer than 

 those of the nymph. 



The subimago having flown ashore, finds shelter from the 

 sun on blades jDf grass, sedges, or among the leaves of trees, 

 and after a period of from twenty-four to thirty- six hours — the 

 length of time being greater or less according to the tempera- 

 ture — the final change to the imago or perfect insect takes place. 

 As a preparatory step, the subimago fixes its claws firmly to 



