286 THE DRY-FLY MAN'S HANDBOOK 



surface on the bank, fixes its claws therein, and pro- 

 ceeds to the next metamorphosis. 



The change is effected very much in the same way 

 as in the Ephemeridse, the thorax, head, and antennae 

 appearing first, and then the wings and legs, followed 

 by the abdomen, and lastly the caudal setse, if the imago 

 has any, and it flutters away leaving the nymphal 

 shuck adhering to the resting-place of the nymph. 



At first the fly which has just issued forth in the 



winged form is flaccid and 



Imago. pallid, but in time it acquires 



its full strength and colour. 

 It is not an insect which is strong on the wing, and 

 hence keeps in the vicinity of the river until sexual 

 intercourse has taken place. This is never attempted 

 in the air. 



Among the giants of the British Perlidse is the large 



stonefly, which is one of three 



Perla cephalotes. species of the genus Perla, and 



the one I have generally found 

 on the chalk-streams is P. cephalotes. Other large 

 species are Perla marginata, Perla maxima. Dicty- 

 opteryx microcephala, another large stonefly, is quite 

 plentiful on the Kennet. These large stoneflies, 

 excepting the last-named on the Kennet, are not 

 plentiful on the south-country chalk-streams, and are 

 seldom present in sufficient numbers to tempt the 

 rising trout. Up north they are plentiful, and the 

 nymph form (generally called a creeper), as well as the 

 winged insect, are among the very best flies to fatten 



