TABLETS OF STONE

When Moses staggered down from the mountain, bent under the weight of ten tablets of stone, he performed one of the greatest con-tricks ever perpetrated upon the human race. A little known fact is that he discarded one of the original Ten Commandments and substituted in its place another of his own creation.

The imposter was the edict which proscribed adultery. Moses reckoned that this would cause less unrest among the Children of Israel than the one which he discarded and which did not re-appear in the literature of the civilised world until G.E.M. Skues penned his epistle known to several generations of anglers as "The Way of a Trout with a Fly".

The original commandment, suppressed by Moses but resurrected by Skues was "Thou shalt not confuse thy imitators with thy attractors, lest the fishes of the river and lake spurn thy piscatorial enticements."

In those heady years following the end of Hitler's War I, together with thousands of fellow fishermen, questioned not the wisdom of this diktat. The contents of our fly boxes were carefully arranged so that the two great genera of fur and feather did not mix.

Traditionally, the artificial flies employed by trout anglers have been classified into two main types - the "imitators" and the "attractors". The majority of dry flies are clearly imitative in nature, most bearing a close resemblance to some aquatic or terrestrial insect which a feeding trout might encounter floating on the surface of the water.

Although a few wet flies, such as the Greenwell's Glory, have always been regarded as imitators, the greater proportion of the group was long relegated by purist fly fishers to the category of attractors which were considered to take fish not by deception but by appealing to some baser instinct of the trout. Patterns such as the Dunkeld, Peter Ross, Alexandra or Bloody Butcher were thought to attract the attention of trout by their bright colours and flashy tinsels rather than by imitating any component of the fishes' diet.

Doubt must now be cast upon this crude classification as we learn more about the entomology of aquatic life and study in detail the diet of trout and the factors which stimulate feeding behaviour.

These thoughts first occurred to me when attempting to analyse the successful artificial flies for a variety of Scottish lochs. Calculating the correlation between fly pattern and fishing conditions threw up an apparent anomaly. The flies which were categorised at attractors were noticeably more successful when the trout were actively rising to natural insects.

In theory, the opposite should have been the case. The old maxim "match the hatch" seemed not to hold a great deal of water when measured against a scientific analysis of the facts.

Clues to this apparent anomaly are to be found in some of the post-Skues literature. Most recently, that excellent book Imitations of the Trout's World contains a wealth of excellent photographic evidence through the lens of Peter Gathercole which is highly enlightening.

One of the most startling effects of scientific study, diligent observation and skilled macro-photography has been the revelation that the colours red, pink, orange and yellow feature strongly in the natural world of emerging insects. Just when the fly is most susceptible to predation by feeding trout, its haemocyanin (equivalent to haemoglobin in mammalian blood) is visible to varying degrees through the hardening body wall.

It appears, therefore, that many of the flies designed by anglers of bygone times are - whether by accident or by trial and error - reasonable imitations of real items from the trout's grocery list. Witness just how often the successful artificial flies of yesteryear were dressed with orange or red tails. The golden pheasant tippets of the Peter Ross, Grouse and Claret or Teal and Green predated any notion that a trout might be attracted by the tinge of blood compounds as an insect prepared for its first flight. And who would have thought that the Bloody Butcher or Hardy's Gold, with their bright red ibis feathers, were unwitting imitations of natural emergers?

The second set of clues to the mystery lies in the study of artificial flies in an aquatic environment. We all recognise the patterns when they sit neatly in our fly box but, in many instances, their appearance alters dramatically when they are submerged in the water.

The hot orange hen hackles of the Kingfisher Butcher or Hardy's Gold, for instance, do not stand out but cling wetly to the gold tinsel body of the fly. The effect is a vibrant translucency which bears a remarkable resemblance to the body of an emerging insect.

Mr Skues may be revolving - indeed spinning - in his grave but the truth of the matter is that many of the flies which he would have classified as attractors are excellent imitations of real life.

These studies also explain the success of flies with pearly body wrappings and with a mixed dubbing construction. In the latter case a dubbing mixture which not only contains a variety of colours but also a number of different textures of material will produce the varied refractive effect which imitates the natural insect to perfection. One of my own favourites for the bodies of dry emergers is a mixture of black seal's fur, fiery brown Antron and a touch of orange wool. With the dubbing well pricked out and a sparse red game cock hackle added, this fly catches more trout for me in a flat evening calm than any other in the fly box.

I am afraid that I have had considerably greater difficulty disproving the antecedents of the adultery commandment!