12 INTRODUCTION. 



upright. They have an infinite variety of size and colour ; some 

 species have well-marked cloudy wings easy of imitation, others 

 have wings which vie with the rainbow in colour and iridescent 

 beauty, of which no entirely satisfactory imitation can be produced. 

 The E-phemeridcB are aquatic insects — the eggs are laid in the water 

 and the larvae live and grow there. Coming to the surface, the 

 larva shakes off its sheath and emerges as a Sub-imago, this later, 

 casts a second sheath and becomes a Spinner or Imago, and it is 

 in this last stage that it bafifles the imitator's skill. Some 

 Ephemeridce have a larval period of twelve months and others 

 three years, hence, the pollution of a stream only once in every 

 three years may be the cause of the disappearance of the large 

 Drakes from so many of our streams. 



The Stone Fhes or Perlidce, of which 40 species are indigenous 

 to this country, are also of interest to anglers — especially on the 

 upper waters of our streams, whose stony beds are the habitat of 

 their larvae. 



Like the Ephemeridce, they begin to show in March or even 

 earlier and are with us to the end of the season. Their larvae 

 prey on other insects, especially the larvae of the smaller Ephemeridce. 

 Their eggs are dropped on the water and hatch into creepers, the 

 following year developing into flies. The Creepers are curious 

 little creatures with big heads and eyes, powerful looking legs, and 

 long tails — the largest being Perla maxima (Fig. 50, plate 5) — 

 and the Creeper of this fly is often used up stream by anglers 

 much the same as a worm. 



In the North of England, fly fishing is of little use for a 

 week or two at least after a good hatch of this insect, so greedily 

 do the fish take it. It has often been stated that the Yellow 

 Sally {JPerla viridissima) is a bitter fly and fish do not care for it. 

 This is a great mistake ; what the fish do not hke is the wretched 

 imitations which are offered in place of this very beautiful fly — 

 a really bright imitation with good light-yeUow glassy wings is 

 taken freely under suitable conditions. 



