| Fly Fishing Devon | "The Heuristic Trout" | Evolution of the wet fly

From drowned insect to 'emerger'

This page explores how wet flies have changed over the last 150 years so that they now:
  • work at various levels in the water column: top, middle and bottom
  • mimic gasses trapped beneath the insect's exoskeleton which help it ascend from the bottom before hatching
  • mimic the bulbous thorax which contains the wing buds
  • mimic emergence of the adult or dun from its immature form whilst breaking through the surface film
  • The sections below describe some important steps in the evolution of the wet fly from early patterns which represent drowned insects to modern patterns which cover each stage in an insect's life-cycle.

    The page concludes with some speculations on the reasons why trout take artificial flies. These ideas are drawn from Paul's earlier academic career which involved research into the stimuli involved in controlling sequences of animal behaviour.

    Winged wet flies

  • these old flies are still effective despite the fact that we now know that very few ephemeroptera hatch from nymph to winged adult   beneath  the water surface
  • often fished with the 'across and downstream' or 'downstream-swing' technique
  • unclear what they represented (cripples, drowned spinners?) and therefore they fell out of widespread use
  • but modern insights into the egg-laying behaviour of some female caddis (see below) may explain their effectiveness and restore their popularity

  • North Country spiders

  • often called 'soft hackled wet flies'
  • may represent emergers, cripples or drowned spinners
  • developed in northern England and southern Scotland (1857-1916)
  • very sparsely dressed - short thin body of silk, one or two turns of hackle
  • fished with short line upstream and a dead-drift, or with a downstream-swing
  • remain an effective style of fly pattern
  • modern revival prompted by Sylvester Neme's book "The Soft Hackled Fly" published in 1975
  • Hanke, Gary (2018). Training tutorial on tying North Country Spiders for Team Canada 2018 Commonwealth Championship. YouTube video Available here
  • Stephen Cheetham's YouTube video: An alternative method of fishing a team of North Country Spiders without using droppers.
  • McPhail, Davie (2021) Tying a Partridge & Orange (Using Up your Large Hackles). YouTube video Available here

  • Cutcliffe's stiff-hackled wet flies

    At a time when North Country writers were advocating thinly dressed soft-hackled flies such as the Partridge and Orange, the North Devon author Cutcliffe (1863) advocated stiff-hackled wingless wet flies for freestone rivers in North and South Devon, as well as those on Dartmoor and Exmoor.

    Over 50 years ago, W.H. Lawrie, in his book English and Welsh Trout Flies, highlighted the unique features of Cutcliffe's book:

  • "The wet fly of the West is a fully-dressed artificial - the very antithesis of the sparsely dressed fly employed for fishing very similar streams in the North Country...
  • So that the fly will respond in a lively fashion to tumbling currents of water, the hackle preferred is a sharp first-quality cock hackle ... [emphasis added]
  • The West-Country fly fisher does not pretend to exact or precise representation ...
  • One of the best books describing the true West-Country trout fly is "The Art of Trout Fishing on Rapid Streams", 1863, by H.C. Cutcliffe... which ought to have enjoyed far greater recognition and popularity than has been accorded to it. It is a pity, and very surprising, that the book should be so scarce as it is.
  • Lawrie then reprints in full all 38 of Cutcliffe's dressings because: "this intensely practical little book is now scarce and not easily obtainable" (Lawrie 1967 p31-33)
  • This problem has been rectified by the an outstanding piece of detective work by a team of enthusiasts led by Paul Gaskell.

    The text of Cutcliffe's book, and high quality photographs of John Shaner's collection of Cutcliffe's flies tied by Roger Woolley, are now available in a book published by Paul Gaskell (2019). This (the first of three) videos tells the story of the 'rediscovey' of Cutcliffe's System for using stiff-hackled wet flies on Devon rivers.

    Cutcliffe fly from video  Wet Fly Special: H.C. Cutcliffe Part 2

    Gaskell's (2019) book is a rich source of information on Cutcliffe's - surprisingly modern - approach to designing and fishing his flies. "Another major contribution he makes is to emphasise "impressionistic" flies over close-copy imitations - particularly in fast water. Again looking to "cutting edge" modern competition nymph patterns ... they are suggestive in size and shape of various types of trout food. At the same time, those patterns are never really "close copy". In fact, they often deliberately include features that are exaggerated or stylised so that they attract fish.

    The fly shown here (No. 37 in Lawrie 1967) illustrates what Cutcliffe called 'conspicuity', and Gaskell terms 'anti-camouflage'. This is an unusual fly; the body consists of bright red worsted ribbed with gold twist. The majority (31 out of 38) of Cutcliffe's other flies were tied with dubbed fur bodies made from a wide range of mixed furs from commonplace Devon animals ranging from house rats to Red Ruby Devon cattle.

    Northern and West Country writers seem relaxed about casting up- or downstream: "On the great questions of fishing up, across, or down stream it is useless to enter ; everything depends upon the size of the river, the condition of the water, and the nature of the bait." (Pritt 1886 p17).  There is no hint here of what would later become Halford's insistence on fishing upstream to a rising fish. Apart from anything else, on Devonshire rivers we seldom see large numbers of duns floating downstream on the surface.

    Pritt and Cutcliffe favoured hackled over winged flies. Pritt clearly identifed his artificial flies as representing a particular stage in an insect's development: "Trout undoubtedly take a hackled fly for the insect just rising from the pupa in a half-drowned state ; and the opening and closing of the fibres of the feathers give it an appearance of vitality...".  But he recognised that winged imitations were necessary on chalkstreams where: "...it is often necessary to fish what is called the " dry " fly.", but notes with wry wit that ".. the May-fly proper, which sits upon the water like some stately winged queen from fairy land, is not common in Yorkshire.."  (Pritt 1886 p19-21). Cutcliffe described wings on a wet fly as looking .. more like a little roll of the dung of a rat than a fly .. Cutcliffe 1863 p119)

    Tying a Cutcliffe Wet Fly

    Chapter V (5) in Cutcliffe's book is a masterclass in fishing local rain-fed Devonshire rivers. He favours hackled flies with picked-out hare's flax bodies ribbed with gold twist (today's Gold Ribbed Hare's Ear). In low water, on bright sunny days, he uses the fly illustrated above with a body "the colour of an infantry soldier's coat, with a ginger-red hackle and gold twist.. the only objection I know to them is, that they catch so many trout that their bodies wear out by the constant biting and tearing of the fish's teeth. "

    He stresses the need for concealment, and what we call today, presentation on these rapid rain-fed rivers. He advocates fishing upstream with two flies on a short line with a cast made with stiff gut because accuracy is important when he is casting into small pockets of water as small as a square foot or less (p113).

    Cutcliffe appreciates that a trout can take a fly almost as soon as it drops on the water (1863 p114): "the instant they pitch they will be darted at, and as quickly must the fish be struck" (p119). This is a most important point. I emphasise to first-timers on local rivers to "watch their fly like a hawk" as soon as it lands, and then relax after a few seconds to avoid unnecesary fatigue. These trout may not engage in long down-stream inspections underneath a fly unless they are in relatively slow-moving pools.

    On page 118 Cutcliffe (1863) specifically rejects - for rapid streams - the idea put forward by other writers that the artificial fly should imitate the natural insect. He says that his 'stretcher' (point) fly is unlike anything he has seen in nature: "a large humble bee with a smart military jacket". He suggests that many of the other flies he uses resemble larva or pupa. This is consistent with his use of animal furs to dress quite chunky bodies on the majority of his patterns.

    Cutcliffe's approach to fly fishing on rapid freestone rivers reminded me of another doctor, Dr William Baigent (1862-1935). Both men had strong views about hackles, and rejected precise imitation of the natural. At a time when Halford's dictum reigned supreme, Baigent favoured fishing with two flies - a nymph below a dry fly - the Dry-Dropper duo method. This is similar to Cutcliffe's 'bob' fly that he fished with a taut line for "dapping / floating about on the surface of the water" (Cutcliffe 1863 p84, 114, 117).

    Cutcliffe viewed the bob fly as performing the function of what we would call a dry-fly indicator (p159-60). He expected to catch fish on his bob fly, and fashioned it to "act the more deceptive and quieter part", and resemble "any indeed which happen to be about the water at the time" (p118). Clearly he was fishing a dry fly, as were many others, before Halford popularised a restrictive form of dry-fly fishing on chalkstreams (Gingrich Chapter 10 1974).

    On relatively shallow South Devon rivers, when trout are feeding on or just below the surface, I fish with two flies on my leader - one dry the other wet - and use the dry fly to indicate when the wet fly has been taken. This also gives you the chance of a fish taking the wet fly even if the dry fly drags. This method appeals to me because it recognises the problems faced by a fish that feeds oportunistically.

    What leaders were used by Cutcliffe? On page 160 he gives the answer; relatively short, stiff and strong. Paul Gaskell consulted Andrew Herd about the length of the gut 'links' used in Cutcliffe's time: "The average piece of European gut was 18 inches at the very most, withe the majority of pieces being between 11 and 16 inches" Gaskell (2019 p28). As a fishing guide there are certain topics I have learnt to avoid with experienced anglers who hold strong views - leader design and length is one of them.

    Skues admired Cutcliffe's book, but was rather dismissive of Cutcliffe's flies; he called them 'lures': "Cutcliffe's "Trout Fly Fishing on Rapid Streams", one of the most intelligent works on fly fishing ever written, explores a corner of the subject, but his patterns are mainly lures" (Skues 1914 pX)

    One can always rely on Datus Proper to introduce an interesting note of gentle controversy when he spots a contradiction between fly-tying convention, and on stream fly-fishing practice. He points out that British writers recommended fishing upstream with wet flies tyed with soft hen hackles. For example, W.C. Stewart in The Practical Angler (1857). Proper agrees that soft hackles are suitable for an upstream presentation. But American anglers tend to cast wet flies downstream: "I have seen many American anglers fishing downstream with wet flies. I have never seen one fishing traditional wet flies upstream." (Proper 1993 p203). I certainly got the impression from Hughes (2015) that American anglers swing wet flies downstream.

    Proper suggests that we try fishing downstream with a stiff-hackled fly as Cutcliffe did to provide mobility against the current.

    One of the unique features of Gaskell's book is the clear photographs of Cutcliffe's flies. An immediate feature that struck me is how similar they are to each other, particularly as regards shape and form of the largely fur bodies. But there are differences as a result of fur being mixed to match the hackle. Cutcliffe's approach to fly-tying was to start with a good brilliant hackle: depend on it if we have brilliancy of [hackle] colour to stimulate the trout, and harmony of [fur] shades, in copy of nature, we shall, for rapid stream fishing, find our fly of the greatest practical utility." (Gaskell 2019 p55). This explains, to me, the variety of fur mixtures used across the 38 patterns.

    The reductionist scientist in my whispers that Cutcliffe's fur bodies are effective because the fur serves to trap bubbles of air. The stiff hackles are structural devices that resist being folded back around the body, and serve to keep the fly just below the surface.

    Roger Fogg records that Cutcliffe had a specific influence on the innovative American Leisenring : "Leisenring adopted the the stiff and sparkling cock hackles in his fast water patterns, reserving soft-hackled versions for moderate and slow currents." [emphasis added] (Fogg 1979 p293).

    Note the similarity in Cutcliffe's bushy body hackled flies to Hidy's flymphs.

    Skues unweighted nymphs

  • introduced (1921-1939) by Skues for use on chalk streams - relatively clear and slow-flowing rivers
  • incorporate a distinct dark coloured thorax to represent wing cases
  • unweighted flies fished across and upstream just beneath the surface  with minimal movement  - dead-drift
  • Skues targeted trout showing 'bulging' rises to pre-emergent nymphs prior to a hatch
  • can be difficult to detect the take unless water surface is relatively smooth

  • Sawyer's weighted nymphs

  • Skue's method developed further by Frank Sawyer who introduced the  weighted Pheasant Tail nymph which was dead-drifted and also moved  to provoke an 'induced take' 
  • method developed for catching trout that are often visible in clear chalkstreams
  • nymph cast upstream of trout so it sinks to trout's level 
  • then rod tip is lifted - the 'induced take' technique
  • The simplicity of this fly suggests to me that Sawyer may have stumbled upon important stimuli that elicit a trout's feeding response: upward movement and the ratio between thorax and body size and shape


    Bill Shuck  tying a flymph using a Leisenring/Hidy style dubbed silk body.

  • term 'flymph' describes the transitional hatching stage between nymph (or pupa) and dun or adult insect
  • introduced (1941-1979) by Hidy and Leisenring - influenced by Skues, called "the American Skues"
  • fished throughout water column with movement e.g. the 'Leisenring lift'
  • shaggy body materials trap gas bubbles - may mimic gas bubbles trapped beneath exoskeleton of pupa and nymph that facilitate ascent and eclosion
  • A very clear step-by-step guide to tying tying a Leisenring Spider is  available here

  • Emergers

    1947 was a good year for emergers. Lawrie's book The Book of the Rough Stream Nymph was also published that year. Lawrie introduced emergers to a British audience: "Deliberate representation of Ephemeroptera at the time of eclosion does not appear to have been dealt with so far in angling literature, so what follows is in the nature of breaking new ground." He went on to define two features that an emerger must include: a subaqueous shuck, with the emerged head and shoulder [thorax] floating on the surface supported by hackle.

  • Advances in macro photography enable us to study insect metamorphosis in great detail at each stage of the life cycle
  • Advances in our understanding of animal behaviour reveal that artificial trout flies are probably effective because they incorporate 'trigger' elements found in the natural insect
  • The  law of heterogeneous summation  could explain how incorporating several 'triggers' into an artificial fly increases its attractiveness to trout. In fact, the law suggests that these artificial flies could be more attractive to trout than the natural insects they are supposed to represent

  • Bob Wyatts Deer Hair Emerger

  • Bob Wyatts Deer Hair Emerger is probably the first conscious attempt to design a trout fly based on what ethologists / behavioural ecologists call 'sign stimuli'. According to Wyatt:
  • "Borrowing the essential features of Fran Better’s Haystack and Usual, Al Caucci’s ComparaDun, and Hans van Klinken’s Klinkhamer Special, the DHE is designed to present a strong prey-image. It incorporates a couple of primary stimuli, or ‘triggers’: a visible wing and a sunk abdomen. While suggesting natural aspects of the insect, these exaggerated features ensure that the fly will be noticed - what behavioral ecologists call a  super-normal stimulus."
  • This  article  explores the application of ethology to the design of trout flies

  • Nymphs tied with modern materials

    Yvon Chouinard uses Peacock Hareline Ice Dub to create the thorax of his Pheasant tail & Partridge wet fly this may represent the air bubble beneath the outer skin of the ascending nymph, as well as the air bubble trapped between the wings of the egg-laying female.

    Trapped  air / gas bubbles  may account for the success of the 'flashback' feature in modern nymphs as well as Chris Dore's Glister Nymph 


  • Cheetham, Stephen (2011). YouTube video: An alternative method of fishing a team of North Country Spiders without using droppers.
  • Hanke, Gary (2018). Training tutorial on tying North Country Spiders for Team Canada 2018 Commonwealth Championship. YouTube video Available here
  • McPhail, Davie (2021) Tying a Partridge & Orange (Using Up your Large Hackles). YouTube video Available here
  • Gingrich, Arnold. (1974) "The Fishing in Print: A guided tour through five centuries of angling literature". Winchester Press. Available online
  • Hughes, Dave (2015). "Wet Flies: Tying and Fishing Soft-Hackles, Flymphs, Winged Wets, and All-Fur Wet Flies". Stackpole Books.
  • Proper, Datus.(1993) "What the Trout Said: About the Design of Trout Flies and Other Mysteries". Swan Hill Press.
  • Fogg W.S. Roger (1979). "The Art of the Wet Fly". Adam and Charles Black Ltd.
  • Skues, G. E. M. (1914). Minor Tactics of the Chalk Stream and Kindred Studies (2nd ed.). London: A & C Black. Available online
  • Price S.D. (Taff). (1976) "Rough Stream Trout Flies". Adam and Charles Black.
  • Pritt T.E. (1886). "North-Country Flies". 2nd Edition. Gilbert and Rivington Ltd. Available online
  • Lawrie W.H. (1967). English and Welsh Trout Flies. Frederick Muller Ltd.
  • Lawrie W.H. (1947). The Book of the Rough Stream Nymph. Oliver and Boyd Ltd.
  • Gaskell, Paul, and John Pearson (2019). "Wet Fly Special: H.C. Cutcliffe Part 2". YouTube video available here
  • Gaskell, Paul (Author) and Stephen Shaner (Photographer) (2019) "Fly Fishing Master H.C. Cutcliffe Rediscovered in The Art of Trout Fishing in Rapid Streams: Including Cutcliffe's original 1863 Text & Roger Woolley's Cutcliffe Fly Collection Photographed in color". Published by the author. Available as a Kindle Edition.
  • Robert Smith, author of The North Country Fly: Yorkshire's Soft Hackled Tradition, has a very useful YouTube channel and website
  • Old Hat Fly Tying is a comprehensive website devoted to  flymphs
  • Cutcliffe H.C. (1863). "The Art of Trout Fishing on Rapid Streams: Comprising a Complete System of Fishing the North Devon Streams, and Their Like". Published by W. Tucker, South Molton. Available online
  • An excellent   video  showing how to tie a North Country spider pattern the Partridge and Yellow
  • "From nymph to flymph": Allen McGee's   article  on history and development of the flymph

  • 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.

    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


    In this video Bob Wyatt ties his Snowy 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.

    This article 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.