Loch Leven Trout 231 



Besides these four principal streams, many other smaller streams 

 and springs contribute their share, and the whole uniting in one body 

 become the source of the river Leven. For several miles from the 

 outlet the river contains trout as large as there are in Loch Leven 

 itself; but below this the river is so much polluted with poison that 

 even the eel fry are killed. The chief food of the trout is the larvae 

 and flies of the blood-worm, which begin to appear early in April, and 

 are usually most numerous about the 2Oth of that month. They first 

 make their appearance within 2 miles of the outlet from Duncan's 

 corner to the sluices ; and also in that part of the loch between the 

 sluices and the " Narrow Neck," including the " Hole of the Inch." 



The larva of the blood-worm, which lives in the mud, is about an 

 inch long, blood-red in colour, and about the thickness of a stocking 

 needle. In April the perfect insect often retains the blood colour 

 of the larva. There are several varieties, but this is the principal 

 one. Hundreds of Loch Leven trout which I have opened from 

 April to September contained both larvae and flies of the blood- 

 worm. The larvae of this fly have the power of rising to the surface 

 and falling to the bottom again, and while in this state trout 

 devour large numbers of them. In my opinion, the most important 

 food of the trout in Great Britain, though little known to anglers, is 

 the fly and larva of the blood-worm. One can have little idea of the 

 immense swarms which appear on Loch Leven unless they have 

 personally witnessed this wonderful sight. As the season advances 

 more appear in the evening than during the day, and on warm nights 

 the surface of the water is almost covered with them, and it is then 

 the trout are to be seen " boiling " all over the loch. 



Next in importance is the olive dun, both the fly and larva ot 

 which are greatly sought after by the trout. 1 1 is one of the Ephemerae, 

 and usually makes its appearance about the beginning of May, and con- 

 tinues till the middle of October. There is both a large and a small 

 kind. Besides the trout, gulls, terns, and swallows feed largely upon 

 them. The trout also obtain part of their food-supply from stone-flies, 

 caddis-flies, and their larvae, also a small fly, Cain, one of the smaller 



