Dry FliesSparkle Dun Variant
This variant on Craig Matthews' Improved Sparkle Dun swaps in bronze mallard barbs alongside pale silver Z-lon for the trailing shuck, running the same strands forward as a shellback and finishing with an olive Argentinean hare thorax under a deer hair wing. Hans Weilenmann's version keeps the shuck's suggestion of a nymphal case while adding mallard barring for texture.
Spring, Summer, Fall
Intermediate
Trout
Feb 2026
Overview
Bare tying thread forms the body, kept slim while bronze mallard barbs and sparse pale silver Z-lon are tied short at the rear as a shuck, then carried forward over the back as a shellback rather than trimmed away. Olive Argentinean hare dubbing builds the thorax, and a deer hair wing stands the fly up in the film. Hans Weilenmann built this as a variation on Craig Matthews' Improved Sparkle Dun, aimed at mayfly duns during a hatch. The trailing shuck and shellback combination lets the fly sit low with its tail dragging in the surface film, matching a dun still shedding its nymphal skin.
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Materials
- Hook:
- Grip 14723BL #14
- Thread:
- Benecchi 12/0, olive
- Wing:
- Deer hair (see note)
- Body:
- Tying thread
- Tail/shuck:
- Bronze mallard barbs; Z-lon, pale silver - tied short
- Shellback:
- Continuation of tail/shuck
- Thorax:
- Argentinean hare, olive
Behavior & Presentation
Natural Behavior: Mayfly duns emerge during specific hatch windows, creating dense concentrations of floating insects that ride the surface film with wings held vertically. Fish develop selective feeding rhythms during these hatches, sipping duns with confidence because the sheer abundance makes feeding efficient.
Where Trout Eat It: Fish sip emergers trapped in the film during mayfly hatches in slow glides, riffles, and seams. The trailing shuck and low-riding profile work when trout feed selectively on emergers.
How to Fish It: Dead-drift with sparse wing riding low in film. Use long, fine leaders (9-12 ft to 5X-6X) for drag-free drifts with delicate upstream casts.
Best Water: Slow glides and riffle edges where mayflies emerge, tailwater tail-outs during hatch windows.
Strike Type: During selective feeding, watch for quiet, rhythmic sips—fish taking emergers often create subtle rings without breaking the surface. The low-riding profile generates gentle takes that can be nearly silent.
Fishing Strategy
Rigging Suggestions: Fish on 9-12 foot leader with 4X-5X tippet. Can be used as the lead fly in a dry-dropper rig.
Seasonal Timing: Most effective during , , and hatches. Fish this pattern when conditions match the natural prey it imitates.
Pro Tips: Floats well with proper floatant application. The natural materials provide good visibility without spooking wary fish.
Entomology
Mayfly duns emerge during specific hatch windows, creating dense concentrations of floating insects that ride the surface film with wings held vertically. Fish develop selective feeding rhythms during these hatches, sipping duns with confidence because the sheer abundance makes feeding efficient.
- Order
- Ephemeroptera
- Common Name
- Mayfly
- Organism Type
- insect
- Life Stage
- adult
