oc Weven” Prout a 
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 larvze 
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 larve 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 who has not seen them can 
have little idea of the immense swarms that appear on Loch Leven. 
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 the trout suck them down everywhere. 
Next in importance is the olive dun, both the fly and larva of 
which are greatly sought after by the trout. It is one of the Ephemera, 
and usually makes its appearance about the beginning of May, and 
continues 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, the smaller 
Ephemere. At certain seasons, too, they feed on shellfish, which are 
2D 
