Reasoning from the appearance of artificial flies in general, it would seem that on a fretted surface almost any one of the many hundreds should get a rise from a fish, if in a biting mood, and, indeed, this is in a measure true. But one swallow does not make a summer. There are times and places when any old thing, even a bit of colored rag, will coax a rise. I have had good success with a bit of the skin of a chicken neck with a feather or two attached. Then there are times when nothing but natural bait proves alluring.
Why a Trout Takes a Fly
We may assume as almost a self-evident proposition that a fish takes an artificial fly under the delusion that it is a natural one, or something good to eat—otherwise it would not take it at all. If this assumption is correct, then it would follow that the best imitations of natural flies or insects should be the most successful. This is, in the main, a reasonable conclusion, though on the other hand certain flies that are universally considered and used as good ones, do not, to our eyes at least, bear any resemblance to any known insect—for instance the coachman, professor and other so-called fancy flies.
The Angler's Viewpoint
An artificial fly on the ruffled surface of the water presents a very different appearance to the same fly when held in one's hand, even to our own eyes; what, then, does it look like to the fish? That's the question. I have often attempted to solve it by diving beneath and viewing the fly on the surface. If the water was perfectly clear and calm, without a ripple, it simply looked like a dark fly, no matter what its color, though I could sometimes discern the lighter color of the wings when formed of undyed mallard or wood-duck feathers. When the surface was ruffled it was so indistinct that a bit of leaf would have seemed the same. A somewhat similar experiment may be performed, in a minor degree, by placing a mirror at the bottom of a barrel of water and viewing the reflection of the fly on the surface.
The Trout's Viewpoint
We can surmise that fish are not color-blind, otherwise there would be no reason for the beautiful colors that many male fishes assume during the breeding season. Fishes are possessed of keen vision, and possibly have the faculty of distinguishing colors in a fly, even when on a fretted surface, where to our eyes they are very indistinct, and where even the form can not be well defined.
Flies in Their Season
In Great Britain it is the rule to use certain flies at different seasons, that is, to employ the imitations of such natural flies as are on the water at the time. This seems quite reasonable in view of the fact that the trout streams there are shallow, and especially so in the case of the chalk-streams whose bright colored bottoms may enhance the visual powers of the fish in discerning, by the reflected light, the form and colors of the artificial fly.
Imitations of Natural Flies