THE GRANNOM 



55 



chiefly in providing an immense quantity of 

 food for the trout at the season when they require 

 it most i.e. quite early in the spring in south- 

 country streams. It goes without saying that 

 the fish feed freely on it in all its stages larva, 

 nymph, and winged. On some rivers, notably 

 the Kennet, the grannom makes its appear- 

 ance towards the middle of April in extraordi- 



FlG. 27. Larvae of Brachycentrus subnubilus (grannom) emerging 

 from the eggs, from a microscope preparation. 



nary abundance, and on this river I have seen 

 the water covered from bank to bank with 

 the discarded pupal shucks. On the Tummel 

 in the Scottish Highlands the fly is not so 

 early, and may be expected towards the end 

 of May or even the beginning of June. 



The artificial pattern is usually a copy of 

 the female insect, which, towards the period 



