The mayfly and the fly fisherman

© Colin Ebdon Prize Winner National Insect Week 2008

Guest author: Malcolm Greenhalgh, naturalist, fly fisherman and author of ‘The Floating Fly’ and ‘The Mayfly and the Trout’

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I am taking mayflies as being the Order Ephemeroptera, that I prefer to call the upwinged flies, as the term causes confusion with the real mayfly, Ephemera danica, in which the dun (or subimago) and spinner (imago) are on the wing in  the period May-early July.

Traditionally North Country (of England ed.) fly-fishers fished a style that is completely different to the style fished on southern chalk streams. There, from about 1870, the use of the dry fly became so dominant that it became the  unquestioned rule. There a floating fly with some resemblance to the natural fly is cast to a trout that has just taken a real fly from the water surface. Here in the North Country (and I include Derbyshire/Staffordshire in this) finely dressed wet flies were mostly used that have only a passing resemblance of the real fly, and they fish below the surface (usually in the top 2-5cm). If trout are rising, they may be cast to identified fish; but mostly these North Country wet flies were fished into any likely palce that might hold a trout. In recent years this traditional North Country style has diminished greatly in popularity, and many fly-fishers in this region now use floating flies.

Waterhen Bloa (Image: North Country Angler)

Waterhen Bloa (left) is an example of this style of traditional fly, with its sparse body and few soft hackle fibres.

In the late 19th century and through most of the 20th, fly-fishers were mostly concerned with size and colour in their artificial floating flies because they believed that trout could spot subtle shades and used colour to identify those flies that they ate. In one famous instance, even the turbinate eyes were matched by using ‘One turn of horse hair, dyed van Dyke brown.’ But from the 1950s or 1960s we realised that trout do not have such an acute vision when looking at a floating fly, and that size, shape (silhouette) and position in the water in relation to the surface film are far more important. This latter has become vital, allowing fly-fishers to catch trout that they might otherwise not have caught with traditional dry flies as used on southern chalk streams. So let me now describe the four categories of flies that we use to catch trout eating mayflies.

Kite's Imperial (image: John Bernard Sunderland. YTye Flies)

1. The traditional dry fly: This has a tail (often a bunch of hackle fibres that stick together as a clump, so do not really match the mayfly setae), a body (often with a ribbing to mimic segmentation) and a stiff hackle taken from a cock’s neck that is wound several times around the hook just behind the eye. Many also have wings that stick up in the air; even in patterns that are meant to match the imago.  Kite’s Imperial is one of the latest of such flies, invented by Major Oliver Kite in the late 1950s (see illustration), and will catch trout and grayling that are feeding on a wide range of mayfly subimagos (e.g. Baetidae, Seratella ignita, Siphlonurus); one selects the appropriate size of artificial fly.
   

   CDC Dun (image: DW Fly Fishing blog)

2. The no-hackle dry fly:This matches the subimago sitting on the water surface. In the traditional fly the hackle holds the front of the fly’s body high off the water and the tails (bunch of fibres) either sink into the surface film or hold the rear of the body off the water. In the real subimago the underside of the thorax and anterior segments of the abdomen are close to the water and the tip of the abdomen and tails are held high off the water. We also have learned that the first trigger that a trout sees of a subimago is the tips of the wings appearing at the edge of its ‘window’ of vision. So we always include a wing. The no-hackle subimago is tied using buoyant materials; for example the CDC Dun, that uses the downy plumes from around the preen gland of a duck; CDC coming from the French ‘cul de canard’. Just vary size and colour.
   

   Ephemera danica (Image: wikipedia)

3. The spent spinner: When female imagos fall onto the water after ovipositing they die flat in the surface film, with wings and tails outstretched, and they are not easy to see. There is one exception, some E. danica imagos die with one wing held up in the air and trout may feed selecively on these and ignore the majority lying completely flat in the surface film. So today we tie our spent spinner patterns flat, with wings, tails and body in one plane, but with a few flies having one wing tied upright to fool pernickety trout! For example, the Orange Quill matches the spent spinners of some Baetis and Ecdyonurusspecies that are abundant on North Country rivers through most of the trout season.
   

   Mayfly emerger (Image: Hatches magazine)

4. The emerger: This is a new style of fly that has been developed since the 1970s. Some of us noticed that sometimes trout would not take every dun that floated over their heads, and after further investigation we discovered that sometimes trout will select flies on the point of emergence, where the abdomen of the subimago is still partly in its larval shuck. We also found that in a significant proportion of at least some species (e.g. Seratella ignita, some Baetis) the tails of the subimago never  leave the larval shuck and the fly never gets off the water; anyone who examines lots of subimagos will find that some have twisted or broken tail filaments, damaged at emergence. The emerger, usually tied on a curved hook, includes a body that is the suggestion of the emptying larval shuck (this dips under the water surface) and then a wing around the base of which is wound a stuff cock hackle. The latter holds the front of the fly in position above the surface and may be taken as matching the legs of the emerging subimago.

Note that on some rivers, the latter has been outlawed because it catches too many trout (i.e. it better matches what the trout are eating)!

In the past decade many rivers, especially in the south of England, have lost most of the Ephemeroptera. Happily here in northern England we still have great hatches of subimagos and falls of imagos, beginning in early spring with Baetis rhodani and ending with S. ignita in late October or early November. Thus the mayflies dominate our fly-fishing…though often other groups, such as the Chironomidae and the Trichoptera are eagerly pigged on by the trout and must be matched by appropriate artificial flies.