The various mayflies in the streams of Yellowstone National Park. The nymph is weighted and designed to stay on or near the bottom. The emerging nymphs is often the same fly, with no weight. It imitates those mayflies that hatch in the surface skim just before it hatches. It should be fished near or in the surface skim. The emerging dun with a trailing shuck is part shuck and part dun. It imitates the hatching mayfly and should be fished in the surface skim. The dun is a dry fly that should be fished on the surface imitating the mayfly dun before it departs the water. It can also be used to imitate those females that deposit their eggs on the surface. The emerging adult is a wet fly designed to imitate those mayflies that hatch below the surface from the bottom to near the surface. The spinner is a spent dry fly that imitates the dead or dying mayflies.
Blue-winged Olives:
widespread abundance, abundant distribution
Baetis and Others
Nymphs:
Blue-winged Olive Nymph: 18/20
Emerging Nymphs:
Blue-winged Olive Emerger: 18/20
Emerging Nymphs with Trailing Shuck:
Blue-winged Olive Emerger with TS: 18/20
Duns:
Blue-winged Olive Dun: 18/20
Spinners:
Blue-winged Olive Spinner: 18/20
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Blue Quill and Mahogany Duns:
Paraleptophlebia species
Abundant, common distribution
Nymphs:
Mahogany Dun Nymph: 18
Emerging Nymphs:
Mahogany Dun Emerger: 16/18
Emerging Dun with Trailing Shuck:
Mahogany Dun Emerger with TS: 18
Duns:
Mahogany Dun: 18
Spinners:
Mahogany Dun Spinner: 18
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Yellow Quill/Pink Ladies:
Epeorus albertae
Abundant, scattered distribution
Nymphs:
Yellow Quill Nymph: 14
Emerging Nymphs:
Yellow Quill Emerger: 14
Emerging Dun with Trailing Shuck:
Yellow Quill Emerger with TS: 14
Duns:
Yellow Quill Dun: 14
Spinners:
Yellow Quill Spinner: 14
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Pale Morning Duns:
Ephemerella species
Very Abundant, widespread distribution
Nymphs:
Pale Morning Dun Nymph: 16/18
Emerging Nymphs:
Pale Morning Dun Emerger: 16/18
Emerging Dun with Trailing Shuck:
Pale Morning Dun Emerger with TS 16/18
Duns:
Pale Morning Dun: 16/18
Spinners:
Pale Morning Dun Spinner: 16/18
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Small Western Dark Hendricksons:
Isolated abundance, slight distribution
Serratella species
Nymphs:
Small Western Dark Hendrickson Nymph: 16
Emerging Nymphs:
Small Western Dark Hendrickson Emerger: 16
Emerging Dun with Trailing Shuck:
Small Western Dark Hendrickson Emerger with
TS: 16
Duns:
Small Western Dark Hendrickson Dun: 16
Spinners:
Small Western Dark Hendrickson Spinner: 16
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Flavs (Lessor Green Drakes):
modest abundance, widespread distribution
Drunella sp
Nymphs:
Small Western Green Drake Nymph: 14/16
Emerging Nymphs:
Small Western Green Drake Emerger: 14/16
Emerging Dun with Trailing Shuck:
Small Western Green Drake Emerger with TS:
14/16
Duns:
Small Western Green Drake Dun: 14/16
Spinners:
Small Western Green Drake Spinner: 14/16
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Tricos:
modest abundance, isolated distribution
Tricorythodes species
Nymphs:
Trico Nymph: 20
Emerging Nymphs:
Trico Emerger: 20
Emerging Dun with Trailing Shuck:
Trico Emerger with TS: 20
Duns: Male:
Trico Dun – Male: 20
Duns: Female:
Trico Dun – Female: 20
Spinners – Male:
Trico Spinner: Male
Spinners – Female:
Trico Spinner Female
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Dark Red Quills:
trickling abundance, isolated distribution
Cinygmula sp
Nymphs:
Dark Red Quill Nymph: 14
Emerging Nymphs:
Dark Red Quill Emerger: 14
Emerging Duns with Trailing Shuck:
Dark Red Quill Emerger with TS: 14
Duns:
Dark Red Quill Dun: 14
Spinners:
Dark Red Quill Spinner: 14
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Brown Drake:
trickling abundance, isolated distribution
Ephemera simulans
Nymphs:
Brown Drake Nymph: 10
Emerging Nymphs with Trailing Shuck:
Brown Drake Emerger with TS: 10
Duns:
Brown Drake Dun: 10
Spinners:
Brown Drake Spinner: 10
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Slate Drake (Great Western
Leadwings):
widespread abundance, isolated distribution
Isonychia bicolor
Nymphs:
Slate Drake Nymph: 10/12
Spinners:
Slate Drake Spinner: 10/12
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Western March Browns:
very abundant, common distribution
Rhithrogena species
Nymphs:
March Brown Nymph: 12/14
Emerging Nymphs:
March Brown Emerger: 12/14
Emerging Duns with Trailing Shuck:
March Brown Emerger with TS: 12/14
Duns:
March Brown Dun: 12/14
Spinners:
March Brown Spinner: 12/14
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Gray Drakes:
Modest abundant, isolated distribution
Siphlonurus species
Nymphs:
Gray Drake Nymph: 10/12
Spinners:
Gray Drake Spinner: 10/12
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Speckle Wings:
Modest abundance, very isolated distribution
Callibaetis species
Nymphs:
Speckled Wing Quill Nymph: 12/14/16
Emergng Nymphs:
Speckled Wing Quill Emerger: 12/14/16
Emerging Duns with Trailing Shuck:
Speckled Wing Quill Emerger with TS: 12/14/16
Duns:
Speckled Wing Quill Dun: 12/14/16
Spinners:
Speckled Wing Quill Spinner: 12/14/16
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Pale Evening Duns:
Modest abundance, isolated distribution
Heptagenia Group, Leucrocuta, Cinygma, Nixe
sp
Nymphs:
Pale Evening Dun Nymph: 14
Emerging Nymphs:
Pale Evening Dun Emerger: 14
Emerging Duns with Trailing Shuck:
Pale Evening Dun Emerger with TS: 14
Duns:
Pale Evening Dun: 14
Spinners:
Pale Evening Dun Spinner: 14
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Western Green Drakes:
very abundant, common distribution
Drunella species
Nymphs:
Western Green Drake Nymph: 8/10/12
Emerging Nymphs:
Western Green Drake Emerger: 8/10/12
Emerging Duns with Trailing Shuck:
Western Green Drake Emerger with TS: 8/10/12
Duns:
Western Green Drake Dun: 8/10/12
Spinners:
Western Green Drake Spinner: 8/10/12
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Copyright 2009 James Marsh
Click below for a list of flies:
Mayflies
Caddisflies
Stoneflies
Midges
Streamers
Terrestrials