| Fly Fishing Devon | "The Heuristic Trout" |The Christmas Tree Theory of Super-Stimulus Trout Flies

Summary: "The Christmas Tree Theory of Super-Stimulus Trout Flies"

This essay starts with a question "Is there a special property of hare's ear fur that is responsible for its long history in the construction of artificial trout flies?" A similar question was asked by Skues 100 years ago, and we still don't have a satisfactory answer.

The Gold-Ribbed Hare's Ear was acknowledged as a very effective dry and wet fly in the 19th century, but was abandoned by Halford for an ideological reason.

Despite Halford's rebuttal, hare's ear continued to flourish as a dubbing material, especially for the construction of sub-surface flies: nymphs, emergers and flymphs.

V.S. "Pete" Hidy exposed the underlying reason for hare's fur effectiveness in 1960, and through the 1970s. But I'm not convinced that his insight has been widely appreciated. Does it matter? I think it does, because as Skues wrote: "If we had that information progress might be possible" (Skues 1921 p91) "

The essay then explores another fly that challenged the persistent influence of the Halfordian approach to fly-tying "It was the “Rackelhanen” that set me free from old traditions , made me innovative and allowed me to think differently."  (Hans van Klinken 2017)

The essay ends with my simple way of thinking about what makes a super-stimulus trout fly: my "Christmas tree theory". A theory for a scientist is just a way of explaining a group of related concepts and findings. It's the scientist's version of a fly box - a container with compartments for fly storage.

In  The Heuristic Trout  there are repeated mentions of the inclusion of fur from the European hare, and snowshoe hare, in constructing effective trout flies. I have gathered them together in this essay which tries to understand the reason(s) responsible for their use down the ages.

Robert Smith,  and American author Tom Travis (2015), trace the history of the use of hare's ear fur in artificial flies ranging from Walton’s fifth edition of the Compleat Angler in 1676, through variations of the Gold-Ribbed Hare's Ear (GRHE) including Bob Wyatt's Deer Hair Emerger.

The Gold Ribbed Hare's Ear: Halford's Achilles' Heel ?

An extract from Why does a trout take your fly?

In Halford's time the Gold Ribbed Hare's Ear (GRHE) was, and continues to be, a very effective pattern. It doesn't look like any natural fly. Halford added wings to make it acceptable to dry fly purists, without any deterioration in its attractiveness to trout. In this comment from his 1886 book Halford recognized its effectiveness.

Perhaps a little cruelly, Skues (1921 p91) wrote: At one time the late Mr. F.M. Halford was a great advocate of the Gold-ribbed Hare's Ear [GRHE], but I believe that latterly his enthusiasm for precise imitation induced him to give it up, successful pattern though he knew it to be, because he could not explain its success to his satisfaction.

Was Skues being mischievous when he added: "Still, the Hare's Ear kills. And I should like to know who was the genius who first conceived its possibilities, and how he got at his theory. If we had that information progress might be possible " (Skues 1921 p91) [emphasis added].

In 1889 Halford appreciated that the GRHE was very effective when trout were taking nymphs just below the surface (bulging):  "This pattern is placed first of the series [Group I.— Imitations Of Natural Insects. Section I, — Olive Duns] as the most successful of modern times. From early spring to late autumn it is one of the most killing of all the duns, and is, besides, pre- eminently the fly to be recommended for bulging or tailing fish. It is probably taken for the sub-imago emerging from the larval envelope of the nymph just risen to the surface." (Halford 1889 p147-8)

Halford discarded the GRHE because it simply did not fit into his theory that dry-fly fishing required presenting a fly tied to imitate an identified floating dun. Gary La Fontaine recognised that the GRHE forecast Swisher and Richards' No-Hackle dry flies: ".. In a pique of intellectual integrity or foolhardy sophistry, depending on one's point of view, he abandoned the fly because this ancient no-hackle did not 'cock' like a proper dry fly." (La Fontaine 1990  p253)

Evolution of the Gold-Ribbed Hare's Ear

An extract from Why does a trout take your fly?

What was it that makes the Gold-Ribbed Hare's Ear (GRHE) such an effective artificial fly ? It may be obvious, but the obvious is worth revisiting - the GRHE is the pinnacle of simplicity in artificial trout flies.
  • What does it represent? Halford stated: "It has always been my theory that it is a fair representation of a dun in the act of disentangling itself from the nymphal shuck" (Halford 1913 p87).
  • Courtney Williams agrees with Halford, and suggests that fur produces "the widespread explosions of light caused by the splitting of the nymphal envelope and the struggles of the dun to free itself from it"
  • Courtney Williams then quotes Harding's explanation of the role of hare's hair fibres : ".. the stiffer ones would either penetrate or make fairly large points of light and the softer fibres, with bended ends pointing in all directions, would mark the water with irregular points and lines of light. " (Courtney Williams 1973 p185)
  • What stage in the insect's lifecycle does the GRHE represent? Halford and Courtney Williams are describing what we now call 'emergence'. In contrast, Harding is describing an insect creating a light pattern on the water surface - a dun.
  • Whitelaw (2015 p96) recognised the GRHE's transition from dry to wet fly, but added: "When exactly the winged dun became a wingless nymph is unclear.. Skues is said to have fished the winged hare's ear..".
  • At some point Skues' wingless nymph became the dominant version of the GRHE. I think I'm safe in stating that nowadays the GRHE is sold and fished exclusively as a nymph. This is confirmed by the index in Hughes' weighty tome Trout Flies: The Tier's Reference [4lb 12 oz; 2.17Kg] which has no mention of the GRHE as a dry fly.

    Bob Wyatt uses hair from the hare's ear to create the body of his Deer Hair Sedge {pictured left} and Deer Hair Emerger [pictured right], flies which capture the essence of the Gold-Ribbed Hare's Ear - an effective dry fly abandoned by Halford, and adopted by Skues to represent a nymph.

    The Deer Hair Emerger (DHE) and Deer Hair Sedge (DHS), are essentially modern versions of Halford's winged Gold-Ribbed Hare's Ear. The DHE is tied with a submerged abdomen to represent an emerger inspired by the Klinkhamer Special. Wyatt's designs back several horses; they represent cripples and emergers, as well as acknowledging the role of wing and thorax in triggering a rise (Marinaro, Clarke & Goddard) .

    For an ethologist, the spiky body in these three flies is a good candidate for a sign stimulus that enables trout to capture insects on, or trapped in, the surface film because :
  • Anglers consistently report, over a number of years, that the GRHE is effective in eliciting a  Fixed / Modal Action Pattern  - the rise
  • Anglers have suggested that a light pattern on the surface, that mimics an insect's legs,  trigger the rise  (Harding, Marinaro, Clarke & Goddard)
  • The simplicity of the GRHE is consistent with previous studies that have shown that simple sign stimuli elicit FAPs in fish ( Heschl 1989)
  • When I read  Rob Smith's  history of the use of hare's ear in artificial flies several things stood out:
  • The material has been used as a component in the body of successful trout flies for over 300 years
  • There has been no satisfactory explanation for the success of fur from a hare's ear, and apparently little curiousity about why it is effective. For example,  "Quite what makes the hair fibres from a brown hare’s skin so attractive to trout and grayling is unknown...It seems to our eyes to imitate nothing, but to the waiting trout, it has a mysterious appeal. And that is the conundrum at the very heart of every Hare’s Ear pattern." (Smith undated).
  • That reminded me of Skues comment about the GRHE:  "I should like to know who was the genius who first conceived its possibilities, and how he got at his theory. If we had that information progress might be possible "  (Skues 1921 p91)"
  • Is it possible that what a trout sees is hidden from us? Is there a property of fur that only appears when it is wet? Ralph Cutter devotes a chapter in his book Fish Food (2005) to the range of insects that display gas bubbles. He makes an important point about hare's ear fur, it can trap air bubbles. (Cutter p 43)

    It's possible that the effectiveness of flies that have fur from a hare's ear as a body material is a result of its ability to  trap air - a sign stimulus signalling  food to trout.

    That was Pete Hidy's explanation for the success of 'flymphs', discussed in the next section.

    Flymphs: Hidy's insight into the effectiveness of hare's fur

    Based on How does a trout catch a fly?

    In the 1960s, V.S. "Pete" Hidy coined the term 'flymph' (part fl y,  part  n ymph ) to describe the transition from nymph to adult i.e. an emerger.

    This definition of 'flymph' - and how to present them - appears in an article written by Pete Hidy's son Lance Hidy (2018) who explains that his father made a clear distinction between flymphs, and other wet flies, but appreciated the similarities and differences between flymphs, and the nymphs tied by Skues.

    A larger version of this picture is  available here

    This photograph of flymphs in water shows bubbles of air covering their hackles and bodies. It was originally published in the American magazine  Sports Illustrated  in 1960 in the third of a three part series of articles by V.S. Hidy titled The Art of Wet Fly Fishing.

    Curiously the photograph was published without comment, or an explanation of its significance. It is a very significant photograph, and I think Hidy knew it, but the articles focussed on practical application of the fly-fishing innovations introduced by his mentor Leisenring, and Hidy "shunned attention and refrained from self-promotion " (Lance Hidy 2018).

    In this extract from his Open Letter to the International Society of Flymph Fishermen  (V.S. Hidy 1973) reveals, for the first time, his interest in mimicry before explaining what is being mimicked.

    "So I speak here, for the first time, of "mimicry flymphs" the film of air and the bubble of air that trout often see during the flymphs metamorphosis into adult winged flies" (Hidy, V.S. 1973) [emphasis added].

    "The film and bubble of air capture and radiate light in a manner that trout are familiar with and accept because it is a natural phenomenon." (Hidy V.S. 1973)[emphasis added]

    I have  reviewed the extensive evidence  that aquatic insects radiate light for the reason given by Hidy.

    Later he also spoke of 'hydrofuge': "the new, unfolding wings have a hydrofuge (water resistance) that creates a film or a small bubble of air",  and suggested drying the fly at intervals to restore this property in the flymph (Hidy V.S. 1979 p166).

    Hydrofuge (shedding water) hairs are found on aquatic insects in moving, well‐aerated streams to allow gas exchange, they "offer a purely physical barrier to liquid water and are permeable to its vapour... they enable certain wholly aquatic insects to retain a thin film of air on the surface of their bodies"  (Crisp & Thorpe, 1948, Schroeder et al 2018).

    The somewhat quaintly named website  International Brotherhood of the Flymph  contains a wealth of information including this collection of flies tied by Hidy that illustrate his use of hare's ear and tinsel to mimic the bubbles of air surrounding emerging insects - the transitional stage from nymph to dun.

    I love this   comment   about flymphs: "If you feel that you can improve this pattern by putting a bead on it's head you are missing the point. Golf awaits you!". The point is that flymphs are designed to fish "just below or within a few inches of the surface film"  (Hidy, Lance 2018).

    A larger version of this picture is  available here

    Lance Hidy (2018) pointed out that his father's pictures were possibly the first of their kind to be published in the fly-fishing literature. Pete Hidy (1973) commented on this photograph: "the use of certain dubbings and hackles can create the phenomenon that I identify as mimicry because it goes beyond, but is related to, the quality of translucence"   Hidy added mimicry to a list of features that convey life to an artificial fly: Undercolour, Translucence, Texture, Shape, Proportions, Delicacy, and Vitality, but acknowledged that the artificial only needed to incorporate one or two of these features: "as shown by the nymph imitations of two English anglers, Stewart and Kite".

    Hidy's mentor Leisenring introduced a range of spun tapered fur bodies. But Hidy had a preference for hare's fur: "Above all these, however, are the four colors of fur from the head or the mask of the English hare".  He recommended the Partridge and Hare's Ear to represent caddis, and the Honey Dun tied with hare's fur and honey dun hen hackle for mayflies (Hidy V.S. 1979).

    Hidy's Subsurface Swing from Hidy (2018)

    In his 1979 article Hidy mentions how an angler should control the movement of a flymph; allowing unimpeded drift downstream with mending when there is a current, but adding movement in slow-moving water. It's worth reading Dave Hughes' (2015 p263-266) detailed description of what he calls Hidy's Subsurface Swing, based on his conversation with Hidy in the late 1970s. Two points emerge that are important in the present context - bubbles of air, and movement of the flymph:
  • "The Subsurface Swing calls for fishing with a flymph designed to entrap bubbles of air in its body and hackle, and to take the air underwater."
  • "... you want the line to draw the flymph in a slow arc right across the bow of the rising trout."

  • Hidy (1979) gives this useful advice :  "After you catch a trout, or after the fly becomes soaked through by repeated casting, you should dry it thoroughly with a piece of Kleenex to restore its maximum appeal."  Drying the flymph will restore its ability to entrap bubbles of air.

    Is the hare's ear fur a super-stimulus?

    Hare's ear in a dun

    I think that when used in a dry fly to represent a dun, hare's fur may be a sign stimulus. Courtney Williams said this of hare's ear fibres : ".. the stiffer ones would either penetrate or make fairly large points of light and the softer fibres, with bended ends pointing in all directions, would mark the water with irregular points and lines of light." (Courtney Williams 1973 p185).

    Clarke and Goddard and Marinaro concluded that denting of the mirror by an insect's feet act as the  'primary trigger'   for the trout's rise. "It is these star-bursts of light created by the indentations of the feet of the dun floating on the surface, that are the first trigger to the trout's pedatory mechanism." (Clarke and Goddard 1980, 2005)

    Hare's ear in a flymph, emerger, or nymph

    When used to create a flymph, emerger or nymph, hare's ear traps bubbles of air that may act as sign stimuli  and: "reveal themselves to trout as dazzling, quicksilver images that appear to glow with an inner light."  (Cutter 2005).

    In addition, when a flymph is fished sub-surface, recommended techniques such as Frank Sawyer's Induced Take, Leisenring's Lift, and Hidy's Subsurface Swing', all involve moving the fly. I have suggested that movement  may be a sign stimulus, or even a  super-stimulus.

    When fished sub-surface, the trout will see a reflection of the fly in its mirror. The up-and-down movements of natural and artificial nymphs create horizontal (reflective) symmetry (De Luca et al 2019) in the trout's mirror .It is possible that this symmetrical movement is a super-stimulus.

    Trout live in an environment with a constant stream of inedible debris including bubbles. Therefore the question arises "How can bubbles act as sign stimuli to trigger a rise?". There are two possibilities:
  • the bubbles on a fly are more  conspicuous   because they are seen against the dark body of an insect or artificial fly
  • the bubbles are in a group, and remain grouped together, as the fly moves up and down in the water.

  • A modern approach to creating super-stimuli

    In the late 19th century dubbed fur bodies fell out of favour because of a lack of reliable floatants: "Possibly at some future date a means of thoroughly waterproofing dubbing may be invented, and if so, I venture to predict that the dubbing body will entirely supercede the quill, as being so much more transparent and watery in appearance ..." (Halford 1886 p 14)

    Fifty years ago, Lawrie (1967) outlined a rationale for using dubbed fur bodies in dry flies based on the difficulty in obtaining cock hackles of suitable stiffness to fully support a dry fly in the manner prescribed by Halford, or create the "light patterns" produced by a dun's feet on the water surface identified by Harding. Lawrie's book All-Fur Flies and How to Dress Them  championed the use of all-fur dry flies.

    There is little mention of Lawrie (1967) in today's fly-tying literature but, as Halford (1886) predicted, dubbed bodies are now commonplace. Natural furs have been joined by, and sometimes mixed with, artificial materials that are pretreated to remain buoyant, or trap air bubbles for a lifelike look.

    But, even today, there are very few all-fur flies as championed by Lawrie. Two that spring to mind are Fran Betters' fly he named 'The Usual', and Bob Wyatt's Snowshoe Hare Emerger. Both flies are tied with the fur from a snowshoe rabbit's foot pad which is naturally waterproof, and traps air for insulation. When water is added this may coat the fur with bubbles that mimic, perhaps to a greater extent, the trapped air carried by aquatic insects. Ed Engle writes enthusiastically about this high-floating material that he puts down to the hairs' ability to trap air. He calls snowshoe-hare hair the "Poor Man's CDC". This poor man needed little convincing, and it seems I'm not alone: "waterlogged or slimed up CDC patterns are known to sink like a stone!" (Hans Weilenmann 2011)

    These two flies are joined by Kenneth Boström's fly, the Rackelhanen (constructed from polypropylene yarn); all are graduates from the "Ugly Ducking School of Fly Dressing" which may account for their scarce commercial availability here in the UK.

    Nevertheless, these are important flies in the search for what makes a super-stimulus trout fly because:
  • Each fly uses just one material to make both body and wing.
  • Together they cover surface, and sub-surface, presentation: dry fly (Usual), emerger (Snowshoe Hare Emerger), dry fly and nymph (Rackelhanen).
  • They are constructed from hydrophobic (hydrofuge) material that traps air in bubbles.
  • Snowshoe Hare Emerger

    The Usual

    The Rackelhanen

    The Rackelhanen - inspiration for super-stimulus trout flies ?

    An extract from Supernormal Sign Stimuli & Heterogeneous Summation

    Rackelhanen available from  Luke Bannister.

    The Rackelhanen was developed in 1967 by Kenneth Boström. It is constructed from just one material - polypropylene yarn.

    It's worth reading his  detailed account  of how to fish this 'ugly duckling' -
  • "free floating as a dry fly"
  • "Stripping on the surface. Short and "nervous" pulls, 2 inch long, with a short pause between them. "
  • " Pull the line so that the fly drags under the water surface... Make a short pause, and the fly floats up again"
  • A Black Rackelhanen is an excellent colour for Dartmoor.  Luke Bannister

    Boström described the Rackelhanen as " .. not very beautiful, it's appearance was almost frightful." And this view was initially shared by John Goddard (2002 p51-54) when he was introduced to the Rackelhanen on the Kennet (an English chalkstream) : "I must admit I was very unimpressed when he  [Preben Torp Jacobsen first showed me this new artificial, as it looked just like a lump of dark brown wool thrown on a hook... So far as at a casual glance I could tell, it really bore little resemblance to any form of natural food."

    Goddard's attitude that trout flies should imitate natural flies is evident in this BBC TV programme he made in the 1980s with Brian Clarke.

    Goddard quickly changed his mind when he "..caught a lot of trout on this nondescript pattern.."and it had "accounted for several large and very difficult trout that would not even look at any other pattern so I am now absolutely convinced this is a winner."  Goddard went on to model his Poly-Pupa and Poly-Caddis flies on Boström's Rackelhanen.

    Luke Bannister recommends and supplies Grey, Olive and Black Rackelhanens for West Country rivers; his Yellow Sally fly is tied Rackelhanen-style details here

    Before he met Kenneth Boström, Hans van Klinken the inventor of the Klinkhåmer Special, "tied flies in the traditional English shoulder hackle flies".  He had this to say about the influence of the Rackelhanen on his fly tying: "It was the “Rackelhanen” that set me free from old traditions , made me innovative and allowed me to think differently. In Scandinavia the “Rackelhanen” is still a very popular fly  [e.g. Krogvold]  but worldwide this fly has never got the attention it surely deserves. I have no idea how my fly-fishing would look today without the discovery of the Rackelhanen but that wonderful sedge imitation gave me enormous self-confidence and inspiration to start a completely new way of fly-tying. " (van Klinken 2017) [emphasis added]

    Perhaps unknowingly, Kenneth Boström had handed Hans van Klinken the key to a door that had been shut by  Frederick Halford , and then locked by his followers, in the late 19th and early 20th century.

    The Klinkhåmer Special with its prominent wing and sunk abdomen, fulfills the  two cardinal features  of an effective dry fly identified by Marinaro, as well as Clarke and Goddard:
  • penetration of the trout's mirror at a distance,
  • and gradual appearance of wings as the fly approaches the edge of the trout's window.

  • Hans van Klinken's Klinkhåmer Special was the inspiration behind Bob Wyatt's Deer Hair Emerger [DHE]:  "Unlike a high floating dry pattern, the trout notices a fly like a semi-sunk Klinkhamer Special or my own pet emerger, the DHE, [Deer Hair Emerger] from a greater distance and locks onto it. These flies share the strong triggers of a nymph and the hi visibility of a dry fly. The trout completes its behavioural response to a potential prey item by eating it. To a trout, charged up and in feeding mode, the fact that the fly doesn’t look exactly like the other bugs on the water is outweighed by its built-in behavioural releasers. " (Wyatt 2012). It is considered to be a multi purpose emerger pattern that works equally well on caddis and mayfly hatches (Rakkenes).

    Wyatt's flies are probably the first commercially available modern trout flies designed on a scientific basis:  "Behavioural science terms like ‘behavioural releaser’, ‘supernormal stimulus’, ‘optimal foraging strategy’ and ‘fixed action pattern’ entered my angling vocabulary. Everything just sort of came together and for the first time in my angling life started to make sense." (Wyatt 2012).

    The success of Wyatt's flies may be due to the simplicity of their construction, and use of widely available tying materials, which makes them easy to tie ( Hans Weilenmann undated), and overcomes the problems encountered by earlier innovations such as  Marinaro's Thorax Dun , and Austin's  Tup's Indispensable.

    Rusty Dunn (2019) gives this insight into Fran Betters' Usual fly: Betters was a no-nonsense, blue-collar angler who, in his own words, applied “common sense and simplicity to an art that has been made to appear too complicated.” After all, said Betters, “This isn’t brain surgery, it’s supposed to be fun and relaxing.”

    The underlying simplicity of many animal behaviours has been remarked upon by scientists and fly-fishers:
  • From Nobel Laureate and ethologist Niko Tinbergen: "it is often the case that quite crude tricks suffice, itself perhaps a reflection of animals’ greater reliance on simpler rules of thumb." (comment by Hutchinson & Gigerenzer, 2005).
  • From Vince Marinaro, author of A Modern Dry-Fly Code : "I am continually astonished by the fact that the most killing flies in fly-fishing history are of very simple construction"

  • The Christmas Tree Theory of Some Super-Stimulus Trout Flies

    At its simplest, a theory is a way of explaining a group of related concepts and findings. It's a scientist's version of a fly box - a container with compartments for fly storage.

    A Christmas tree serves as a useful analogy. A Christmas tree is recognizable by its size and shape. Its bare attractiveness is enhanced by lights, and other decorations, strung through the branches.

    Here are some ideas, developed in  The Heuristic Trout,  that led to my 'Christmas Tree Theory' of super-stimulus trout flies.

    Most contemporary fly-fishing literature accepts that precise imitation is neither possible nor necessary. Instead, flies should be designed to resemble the size and shape of a trout's food (Proper 1993). Wyatt uses the phrase 'General Impression of Size and Shape' (GISS) to capture this idea.

    In the same way that GISS enables  planes to be recognized by humans,  GISS enables an artificial fly to be recognized by a trout.

    In order to be recognized as potentially edible, an artificial trout fly needs to be a  prey image  that contains  sign stimuli or triggers  that conform to a trout's  search image

    I have suggested that a  Recognition Heuristic  enables quicker decision-making in a fast-moving environment.

    The logical problem - of a trout selecting an imitation fly amongst a large hatch of identical insects (selectivity) -  spotted by La Branche   exists to this day on rivers with substantial fly hatches. A solution is suggested by Swisher and Richards (2018) : "The right fly is one that resembles the natural so closely that the fish seem to prefer it to the real thing." [emphasis added]

    For an artificial fly to be preferred over the natural, it must qualify as a  supernormal stimulus or super-stimulus.   It must be an exaggerated version of a stimulus to which there is an existing response tendency, or any stimulus that elicits a response more strongly than the stimulus for which it evolved.

    Clarke and Goddard  suggested that denting of the mirror by an insect's feet act as a sign stimulus for the trout's rise. They wrote :"It is these star-bursts of light created by the indentations of the feet of the dun floating on the surface, that are the first trigger to the trout's predatory mechanism." [emphasis added]

    Hidy (V.S. 1973) described a similar visual effect when flies are sub-surface, or in the process of emerging: "The film and bubble of air capture and radiate light in a manner that trout are familiar with and accept because it is a natural phenomenon."  The available  photographic evidence  supports Hidy's conclusion.

    These observations, by experienced fly-fishers, suggest that artificial flies that present an exaggerated form (i.e. multiple scintillating lights ) of the sign stimulus that trout normally react to are super-stimuli in the sense that the term is used by ethologists -an exaggerated version of a stimulus to which there is an existing response tendency.

    Forty years ago, Hidy was forthright in his opposition to the use of synthetic materials to mimic these effects: "Do not use synthetic body materials.... Orlon, nylon and a variety of acrylics that are fine for dry flies ... but useless for flymphs. Natural furs ... have the water resistance that provides the hydrofuge mentioned earlier. Synthetics do not." (Hidy V.S. 1979 p174-5). Nylon is hydrophilic (Padbury 2014), so will not favour the formation of air bubbles.

    More modern materials have overcome this limitation. Gary LaFontaine used Antron to mimic the air bubble on caddis pupae. McGee's book Tying & Fishing Soft-Hackled Nymphs (2007) contains an in-depth description of suitable materials for tying flymphs, comments that "Synthetic dubbing doesn't absorb much water and is sometimes factory pre-treated with floatant, as such it's best used for flymphs or surface flies fished high in the water column".  Synthetic materials can also be added to provide 'flash / sparkle' to hare's fur dubbing.

    Ed Engle (2017) makes a convincing case for the use of artificial materials: "Adding a little flash to a pattern is the most consistent 'trigger' that I have found."  Craig Mathews uses Z-lon for the tail in his Sparkle Dun that imitates the emerging insect's hydrofuge shuck.


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  • Schroeder, T. B. H., Houghtaling, J., Wilts, B. D., Mayer, M.,(2018) Adv. Mater. 2018, 30, 1705322. Available online
  • March, Nicole (2020). "The Usual by Nicole March". Dette Flies Blog. Available online
  • Padbury (2014). "How do you differentiate hydrophillic and hydrophobic polymers?" Available online
  • Swisher, Doug and Richards, Carl. (2018). Selective Trout . Skyhorse. Kindle Edition.
  • Travis, Tom (2015). "Hare's Ear Patterns, Part One". Available online
  • Weilenmann, Hans (2011). "Tying with CDC".Midcurrent Available online
  • Whitelaw, Ian (2015). 'The History of Fly Fishing in Fifty Flies' Arum Press.

  • About the author

    Paul guiding ITV News reporter in June 2019

    with sea trout in camera range ...

    Paul Kenyon lives in Ivybridge on the southern edge of Dartmoor about 6 miles from the Upper Yealm Fishery.

    Paul devotes more time than is reasonable to his love of all things associated with fish, fishing, instruction and guiding on Dartmoor rivers.

    Paul constructed his first web page in Autumn 1993 as a way of distributing lecture notes to undergraduates.

    He retired in 2006 from the Department of Psychology, University of Plymouth where he lectured in behavioural neuroscience and evolutionary psychology.

    email paul@flyfishingdevon.co.uk

    The author's  YouTube channel


    In this video Bob Wyatt ties his Snow Shoe Hare Emerger

    Bob uses this material in place of CDC because he has found that CDC tends to be "a one fish fly" which is an absolute no-no for guides on local rivers.

    These articles would not have been possible without the help and encouragement of Bob Wyatt. Bob is an artist, author, Certified Fly Casting Instructor and long-time angler. Born in Canada, he fished the freestone streams of southwestern Alberta in the late 1950s. He now lives on New Zealand's South Island. His articles have appeared in Fly Fishing & Fly Tying(UK), Gray's Sporting Journal, Fly Rod & Reel, and Flylife Magazine (AU). He has published two books: Trout Hunting: The Pursuit of Happiness (2004) and What Trout Want: The Educated Trout and Other Myths (2013). In this interview by April Vokey he discusses his “prey image” theory, trout fishing and the early days of steelhead fly fishing.