The dun, or sub imago, is stage one of the adult mayfly, the ugly duckling in the line and named due to its colours of browns and beige.
Mayfly duns appear on the surface and remain long enough for their wings to dry before taking flight to seek refuge among the streamside vegetation, where the dun or sub imago moults into the second stage of the adult mayfly, the spinner or imago.
The spinner has much finer features and more distinct colouration than the dun; its wings are also clear and shiny. Spinners are generally black, red or brown and they have the pleasure of the mating ritual, usually on the wing.
Once the mating is complete the females can be seen dipping their tails into the water as they lay their eggs to commence the mayfly life cycle all over again. The male and female spinners, once spent, fall to the surface to be picked by hungry trout.
The adult insect is dull by nature so the tying materials reflect this. The key for this pattern is the profile that the fly makes when it sits on the surface, which is why I cut the hackle flat on the bottom to make the fly sit flat.
There are many and varied ways to fish this pattern, with the most effective to fish it as naturally as possible.
When fishing impoundments or shallow lagoons, work downwind, flicking short casts either side so that the fly drifts naturally on the breeze.
On some of the slower, weed-choked Snowy Mountains and Monaro streams, plonking the fly down in the gaps in the weed often brings some form of response. On the slower pools and glides fish can be polaroided and presented to, but they are spooky, so stealth and a delicate presentation is needed.
Aside from that this is a great general dun imitation and has been used with success in many varied situations in Victoria, Tasmania, New Zealand, and by my friends in Scotland.
TYING INSTRUCTIONS and MATERIALS
|HOOK:||Mustad R50 #12-16|
|THREAD:||Black 6/0 – 8/0|
|BODY:||Stripped peacock quill|
|RIB:||Fine copper wire|
|HACKLE:||Honey dun (Saddle)|
|WING:||Enrico Puglesi intel fibres (March brown)|