We may conclude, then, that as trout are in the habit of feeding on such flies and insects as resort to, or are hatched in, the water, that the best imitations of such natural flies, from the trout's viewpoint, would be the most alluring. I think it goes without saying, that all past experience has proven that the imitations of some of the commonest aquatic insects have been the most successful under all conditions. This would include not only the imago, but the larva, as represented by the various hackle flies.
Dark or Light Colored Flies
The old rule to use light-colored flies on dark days and high or discolored water, and darker flies on bright days, or with low and clear water, has been followed for centuries, and in the main is true and reliable. As some anglers have found that a reversed application of it has been successful, at times, they are inclined to doubt it altogether. However, they do not look at it intelligently. With clear water and a clear atmosphere a light-colored fly will show as plainly on the surface as a dark one to the fish below. If we gaze upward during a fall of snow, the flakes appear quite dark, while on a level or below the eye they appear white. Apparently, then, there are other conditions that must be taken into account. With a sunken fly, for instance, the case is different, for a dark fly then appears more distinct than a light one, in clear water; but with milky or discolored water a bright fly is more easily discerned below the surface—hence the rule. And on the same principle smaller flies are suitable for bright days and clear water, and larger ones for dark days and discolored water.
The Non-Rising of Trout
In a very interesting address delivered before the Anglers Club, of Glasgow, Scotland, on "Why do trout sometimes not rise to the artificial fly?" the lecturer after naming and discussing many of the reasons usually advanced, said:
"And what is the conclusion of the whole matter? Shortly, this—that there is a great deal about the question that we know little or nothing about."
He advised his brother anglers to "Watch narrowly the facts as observed in nature, note them down carefully at the time, compare them with those of brother anglers on occasions such as this, and out of all evolve theories which, when reduced to practice, will be found to have carried us nearer to the truth."
Condition Versus Theory
This is very good advice freely given—and by the way advice is more easily given than reliable information in a case like this. Nevertheless fly-fishers should consider that a "condition, not a theory," confronts them in the rising or non-rising of a trout to an artificial fly, and should endeavor to ascertain, if such be possible, just what conditions are present to account for the peculiar actions, at different times, of those elusive creatures of the adipose fin, that according to popular opinion seem to have as many moods as specks or spots.
A Probable Reason