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Hatch PDF

Henry's Fork Regional Hatch

By: Mike Lawson

May Flies
Mar
April
May
June
July
Aug
Sept
Oct
Nov - Feb

Blue Winged Olive (Baetis, several species)

Brown Drake (Ephemera simulans)

Flavilena (Drunella flavilinea)

Gray Drake (Siphlonurus occidentalis)

Mahogany Dun (Paraleptophlebia bicornuta)

Pale Morning Dun (Ephemerella inermis)

Tiny Olive Dun (Plauditus punctiventris)

Speckled Spinner (Callibaetis ferrugineus)

Trico (Trycorythodes minutus)

Western Green Drake (Drunella grandis)

Western March Brown (Rhithrogena morrisoni)

Caddis Flies
Mar
April
May
June
July
Aug
Sept
Oct
Nov - Feb

Grannom (Brachycentrus)

Spotted Sedge (Hydropsyche)

Other Caddis flies (Several Genera & species)

Stone Flies
Mar
April
May
June
July
Aug
Sept
Oct
Nov - Feb

Golden Stonefly (Acroneuria, classenia)

Salmon Fly (Pteronarcys)

Small Stone Flies (Isoperla, alloperla)

Midges
Mar
April
May
June
July
Aug
Sept
Oct
Nov - Feb

Midge (Chironomidae)

Blue Winged Olive (Baetis)	Nymph Type:	Swimmer	Hook Size:	18 20 22
Characteristics:	Two tails. Light to medium olive/gray body with light to medium gray wings.
Timing of hatches:	Mid-March through Early May, 12:00 PM until 3:00 PM and in the mid-summer around dusk, September through October, from 11:00 AM until 4:00 PM
Habitat:	Widespread on most sections of the Henry's Fork, Madison, Firehole, South Fork of the Snake and other local rivers and tributaries.
Comments:	Many species are multi-brood, meaning a species may produce two or more broods during the calendar year. The most important species emerge in the spring and again, in the fall. These mayflies produce exceptional dry fly fishing during these periods. Egg laying Spinners often crawl under the water to oviposit their eggs.
Patterns:	Pheasant Tail Nymph, Halfback Emerger, CDC Emerger, Paracripple, BWO Soft Hackle, BWO Nohackle, Sparkle Dun, Thorax, and Parachute Adams.

	Nymph Type:	Burrower	Hook Size:	10 12
Characteristics:	Three tails. Slender body. Yellowish tan to light brown with darker markings. Wings are mottled brown, and heavily spotted.
Timing of hatches:	Mid to late June, immediately following the Green Drakes. Duns emerge at or just before dusk. Spinners normally fall about the same time. Some trout will often feed on nymphs or emergers, others on duns and still others on spinners.
Habitat:	Very localized in the very slow sections of the Henry's Fork on the Harriman Park, the Gibbon in Yellowstone Park and other waters. Needs slow water with silt bottom.
Comments:	Brown drakes are very important on the slow sections of the Harriman Park downstream to Pinehaven. Nymphs can swim rapidly prior to emergence. The focal point of the emergence moves gradually upstream a day at a time. The overall emergence period is about two weeks. Brown drakes sometimes also emerge in the morning hours.
Patterns:	Brown Drake Nymph, Emerger, Cripple, Paradrake, Mike's Brown Drake, Brown Drake Partridge Spinner.

	Nymph Type:	Crawler	Hook Size:	14 16
Characteristics:	Three tails. Dark gray wings with medium greenish or brownish olive body.
Timing of hatches:	Late June through July. Duns usually emerge in the late afternoon. Spinners fall in the morning hours. Best activity occurs on cloudy, humid days.
Habitat:	Medium to fast water sections of the Henry's Fork, Madison, Yellowstone and other surrounding waters. Especially common on the Last Chance section of the Henry's Fork and the tailwater section between Ashton and St. Anthony.
Comments:	Flav’s closely resemble their larger cousin, the Western Green Drake. Hatches are sometimes sporadic and undependable. However, trout really love these robust mayflies and it doesn't take many to create a feeding frenzy. The duns emerge slowly on the surface making emergers and cripples top pattern choices.
Patterns:	Pheasant Tail Nymph, Flav Cripple, CDC Emerger, Flav Thorax, Slate Olive No-hackle, BWO Parachute.

	Nymph Type:	Swimmer	Hook Size:	10 12
Characteristics:	Two tails. Dark gray wings with heavy veination. The body is olive gray with dark brown markings. Spinners are more purplish with clear wings.
Timing of hatches:	June into early July. Duns emerge sporadically during mid-morning hours. Spinners fall in the late afternoon and evenings and sometimes mid-morning.
Habitat:	Slow to medium fast water. The Gray Drake is an important hatch on the lower Henry's Fork below Ashton, lower Fall River, the estuaries of the Madison and South Fork of the Madison entering Hebgen Lake, and the Upper Yellowstone River below Yellowstone Lake.
Comments:	The nymphs concentrate in the margins of the stream where they crawl out to emerge. Consequently, the duns are not nearly as significant as the spinners. The mating flights of the spinners creates superb dry fly fishing on the lower Henry's Fork. High water years provide the best Gray Drake activity.
Patterns:	Feather Duster Nymph, Gray Drake Nymph, Gray Drake Spinner, Parachute Adams, Gray Wulff, Adams Parawulff.

	Nymph Type:	Crawler	Hook Size:	16 18
Characteristics:	Three tails. Dark gray wings with streamlined, dark mahogany body.
Timing of hatches:	The most important emergence occurs in late August through early October. Duns emerge during mid morning while spinners fall in the later afternoon to early evening hours.
Habitat:	Slow to medium fast gravel bottom water. Mahogany Duns are common on the Harriman Park stretch of the Henry's Fork, the South Fork of the Snake and several other local waters.
Comments:	The Mahogany Duns provide some of the finest dry fly fishing of the late summer on the Harriman Park and other waters. There are a number of other species that emerge throughout the summer but the late season is the best. Emergence takes place at the surface making an emerging nymph pattern very effective when trout are rising.
Patterns:	Pheasant Tail Nymph, Mahogany Dun Emerger, Mahagony Dun Parachute, Mahogany Dun Thorax, Slate Tan Nohackle

	Nymph Type:	Clinger	Hook Size:	12 14 16
Characteristics:	Two tails. Dark gray wings with strong dark mottling. Body is dark olive brown to purplish black.
Timing of hatches:	Late spring from mid-April through early June. Duns emerge during mid-morning hours. Spinners fall in the evenings.
Habitat:	Medium to fast water with gravel or rocky bottom. Very common on most sections of the Henry's Fork. Late season species are also common on the Madison, Gallatin, and some waters in Yellowstone Park.
Comments:	March Browns provide exceptional dry fly fishing on the Henry's Fork in May and early June. Transformation from the nymph to the dun usually takes place under the water. Therefore, a soft hackle emerger fished deep can often bring good results. During cooler weather the duns will stay on the surface long enough to provide good dry fly action.
Patterns:	Pheasant Tail Nymph, Pheasant Tail Soft Hackle, March Brown Emerger, Quill Gordon, Slate Olive Thorax, Slate Olive Nohackle.

	Larva Type:	Casemaker	Hook Size:	14 16 18
Characteristics:	Sometimes known as the "Mother's Day Caddis" the Common Grannom is a very important hatch in the pre-runoff period in April and May on the Henry's Fork, South Fork and other local wateres. These caddis are second only to the Spotted Sedge in importance for fly-fishers. The case making larvae are a very important food source for over-wintering trout. Another species produces very good fishing on the Henry's Fork, Madison, Yellowstone and other waters during late summer.
Timing of hatches:	April and May and August through early September. Emergence occurs in the afternoon and early evening. Egg laying frequently coincides with the emergence.
Habitat:	All water types. Larvae build square cases. They thrive on gravel, rocks and aquatic vegetation.
Comments:	Pupae can drift long distances while struggling to escape the pupal shuck. Males are one size smaller than females. The emergence often produces explosive rises from trout that are hungry after a long winter. Best technique is to use a pupa as a dropper from a dry fly.
Patterns:	Olive Cased Caddis, Olive or Dark Gray Emergent Sparkle Pupa, Olive Partridge Pupa, Olive Spent Partridge Caddis, Olive X-Caddis, Olive E-Z Caddis, Hemingway Caddis.

	Larva Type:	Net Spinner	Hook Size:	14 16 18
Characteristics:	Far and away the most important group of caddisflies throughout the season. Body is usually cinnamon brown. Wings are brownish gray with small tan spots and blotches. Legs are cinnamon brown. The larvae are net makers. Pupae swim to the surface and emerge in open water. Females dive under the surface to lay eggs. When they are finished, they drift on the surface with the current. Several species are important on the Henry's Fork, Madison, South Fork and other local waters.
Timing of hatches:	June through September. Most emergence occurs in the evening but can occur in the morning or midday. Egg laying can occur morning or evening.
Habitat:	Medium to fast water. Larvae need clean gravel to build their nets.
Comments:	The Spotted Sedge produces some of best caddis fishing. During emergence the emerging pupal imitations are effective when fished just under the surface. Spent and diving caddis patterns are effective during the egg laying flights.
Patterns:	Tan Electric Caddis, Tan Emergent Sparkle Pupa, Tan Partridge Pupa, Tan Spent Partridge Caddis, Tan X-Caddis, Tan E-Z Caddis.

	Larva Types:	Casemakers, Net spinners and Free Roaming	Hook Size:	12 - 22
Characteristics:	Caddisflies are extremely important on all waters of the Henry's Fork region. Their life-cycle consists of an egg, larva, pupa and adult. Most species require a year to complete their life-cycle. The larvae are a very important food source for trout, especially during the winter months. All larvae are classifled into three types: Free roaming, net spinners, and case makers. All form a pupa prior to emergence. The pupae are normally far more important during emergence than adults. The egg-laying process either occurs on the surface or females dive under the suface to lay their eggs.
Timing of hatches:	April through October. Emergence and egg laying commonly occurs during the morning or evening hours.
Habitat:	All water types with various bottom structure.
Comments:	Other caddis hatches pale in comparison to the Spoted Sedge and the Grannom. For most anglers, defining caddisflies as to species is not as important as mayflies. Understanding the biology of caddisflies in comparison to mayflies is very important. Properly imitating the pupae, emerging adult and egg-laying adult as to color, size and shape is the key to success.
Patterns:	Tan Electric Caddis, Tan Emergent Sparkle Pupa, Tan Partridge Pupa, Tan Spent Partridge Caddis, Tan X-Caddis, Tan E-Z Caddis.

	Nymph Type:	Stonefly	Hook Size:	8 10 12
Characteristics:	These large stoneflies are similar in appearance to their larger Salmonfly cousins except they are a couple of hook sizes smaller and they are lighter in color. They are a dark golden amber with a lighter underbelly. The most common species emerge along with or just after the Salmonflies. Their emergence usually covers a longer period. Another species emerges on the South Fork of the Snake in late summer and early autumn.
Timing of hatches:	Henry's Fork: May 25 - June 30; Madison: June 25 - July 20; South Fork: June 25 - July 20 and August 15 - September 15.
Habitat:	Medium to fast, oxygen rich water with rocks and boulders.
Comments:	Nymphs often emerge at night or during the early morning hours. Adults don't always have wings. Many males and some females of the late season species are entirely wingless or they have very small wings rendering them impossible to fly. These species complete their mating ritual on the bank and scurry across the water to lay eggs. Late in the summer trout lay in wait to target these large morsels as they scamper across the water.
Patterns:	Tan Rubberlegs, Golden Stone Nymph, Henry's Fork Golden Stone, Madam-X, Golden Stone Hedge Hog, Elden's Ant.

	Larva and Pupa:	Swimmer	Hook Size:	12 - 24
Characteristics:	Adults have two wings, a slender body and size long legs. Pupae have thin elongated, well-segmented abdomens with a short robust thorax. Most species require only a few weeks to mature. Midges have a complete life cycle consisting of an egg, larva, pupa and adult. The pupa is far more important than the adult or larva. The colors vary widely. The most common colors are olive, brown, tan, gray, and red.
Timing of hatches:	Midges emerge year-round. The pupae emerge in the morning and evening hours. During cool weather they often emerge throughout the day.
Habitat:	All water types. Many species prefer slow water rich in aquatic growth.
Comments:	Best midge fishing on the rivers is during the late fall, winter and early spring. Midge fishing is especially effective on Hebgen Lake and other lakes in the region from ice-out until early July.
Patterns:	Griffith's Gnat, Midge Pupa, Stillborn Midge, Miracle Midge, Suspended Midge, CDC Midge Adult, Tungsten Zebra Midge.

Henry's Fork Regional Hatch

By: Mike Lawson

(Baetis, several species)

Blue Winged Olive(Baetis)

Characteristics:

Timing of hatches:

Habitat:

Comments:

Patterns:

(Ephemera simulans)

Characteristics:

Timing of hatches:

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(Drunella flavilinea)

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(Siphlonurus occidentalis)

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(Paraleptophlebia bicornuta)

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(Ephemerella inermis)

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(Plauditus punctiventris)

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(Callibaetis ferrugineus)

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(Trycorythodes minutus)

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(Drunella grandis)

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(Rhithrogena morrisoni)

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(Brachycentrus)

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(Hydropsyche)

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Blue Winged Olive
(Baetis)