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Stonefly Emergence and Pattern Guide
A Salmon Fly.
The following guide includes general descriptions of the physical characteristics, flight times, and seasons of emergence for the most important stoneflies in the region under the purview of our Trip Planner. Suggested patterns are also given. Individual hatch guides for the most prominent streams in the area, with individualized season information and flight times, are given on the appropriate sub-page in the Our Waters page. Of the "big three" families of insects important to trout in our area: mayflies, caddis, and stoneflies, stoneflies are the least important in duration. When they emerge, however, they are usually the most important flies on the water.
The most important things to remember about stonefly emergences in general are:
1.) All stoneflies crawl to the bank to emerge, meaning there's no such thing as a "stonefly emerger."
2.) Adult stoneflies are available to trout when they fall off streamside branches they're resting on, meaning casts have to be close to the bank, when they hover over the river during mating flights, and when they return to lay eggs.
3.) Nymphs draw tremendous action for some weeks prior to the hatch for the larger, more-important species, provided the water is clear enough.
Please contact us for more information on area hatches and the flies to match them.
The first portion of the following guide consists of an emergence table and notes. The second portion consists of longer descriptions of each listed insect.
Key for the following table:
| First Column: | The first column gives the common name or a descriptive name of the insect. |
| Second Column: | The second column gives the size of the insect. |
| Third Column | The third column gives a visual description of the insect. |
| Remaining Columns: | Remaining columns give the months of emergence. A capitol X signifies a hatch of primary importance, a small x notes a hatch of secondary importance. A blank signifies a month when no hatch is likely. |
Emergence Table
| Name | Size | Description | Emergence Month (X=major, x=minor, space=unlikely) | |||||||||||
| J | F | M | A | M | Jn | Ju | A | S | O | N | D | |||
| Salmonfly (Willow Fly, Giant Black Stonefly) | 2-8, 2 or 3XL | black or dark brown and dirty orange, tan or gray wings with pronounced dark veination. | x | x | X | |||||||||
| Golden Stonefly (Trout Fly, Alder Fly) | 6-10, 2 or 3XL | golden brown and tan, tan or light gray wings. | x | X | X | x | ||||||||
| Yellow Sally | 14-16, 2XL | yellow or mint green, sometimes with a red egg sack, pale gray or off-white wings | X | X | x | |||||||||
| Olive Stone (1) | 12-14, 3XL | olive green body, tan wing | X | x | ||||||||||
| Medium Black Stone (2) | 10-12, 3XL | black body, gray wings | x | |||||||||||
| Brown Stone | 12-14, 2XL | brown body, gray wings | x | x | ||||||||||
| Little Black Stone (Snowfly) | 16, 2XL | black | x | x | x | |||||||||
| Medium Yellow Stone (3) | 12, 2XL | similar to Yellow Sally but trending to tan | x | |||||||||||
Notes:
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1. |
This insect only need be imitated in the Gibbon River Canyon, though I have seen it on the Yellowstone and Gardner as well. |
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2. |
I have not seen this insect described anywhere. It is notable for its coal-black body. It need not be imitated most of the time, as it emerges with the Salmonflies and Golden Stones. |
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3. |
This insect may not exist. Tyer Matt Minch of Gardiner swears that this is a distinct insect from the Yellow Sally, being both somewhat less vivid in coloration and a size or two larger. I noted it for sake of completeness. |
Discussion of Insects
| Common Name | Scientific Name (if known) | Discussion |
| Salmonfly | Pteronarcys californica | The Salmonfly is probably the most well-known hatch in the entire
Rocky Mountain region, and Yellowstone-area rivers are home to some of
the best hatches. The Yellowstone sees a trickle as far downriver as
Livingston, with the core of the hatch from Emigrant upstream all the
way to the head of the Grand Canyon, well into the Park. There are
a few in the reach between the Lake and Upper Falls, as well. The
Gardner and the Lamar (in its canyons) also see excellent hatches, with
spottier emergences on the Madison and in the Firehole Canyon.
Except on the Yellowstone and Gardner, this is a brief hatch, lasting no
more than a week. On the Gardner it can stretch to two weeks and
three on the Yellowstone.
Salmonflies are impossible to mistake for anything else. Salmonflies are large, orange and black or orange and dark brown insects that vaguely resemble locusts. At the peak of the hatch, there are enough mating insects in the air to fill the sky. The hatch tends to move upstream, though in recent years the progression has seldom been orderly, with bugs instead hatching in fits and spurts over several reaches of river at once. The best fishing is found by nymphing immediately ahead of the hatch. The only nymph worth using is a Matts Black "Brooks" Stone. I no longer carry any others, because this fly outperforms all of them at least three to one. The only exception is when using stonefly nymphs for brown trout in the fall, when I prefer something with rubber legs and a dense front hackle, like a Flashback Black Stone. This serves as an irritator rather than an imitator, however, so the point stands. The dry fly fishing is best at the forefront of the hatch or behind it, because the peak frequently finds too many fishermen on the river and the fish either glutted or hook-shy. The best dry flies are: Wiese's Prom Queen Salmonfly, and Roman's Thing from Uranus in foam patterns and the Parks' Salmonfly and Gould's Half Down Salmon in "fur and feather" patterns. I carry one of each, since the primary benefit of foam is its flotation, but you sometimes want a Salmonfly to sink. They don't float well themselves, and egg-layers and others frequently get waterlogged and sucked under slightly. Imitating this is not possible with foam. The Half Down is better late in the hatch because it imitates an egg-layer, while the Parks' works at any stage because its thick hackle suggests a fly trying to get airborne again. Salmonflies are creatures of fast water and emergence times vary by several weeks due to differences in water temperature and level, so keep your eyes on our Fishing Report to know when to expect the hatch on a given body of water. |
| Golden Stone | Hesperoperla pacifica | Golden Stones are almost as large and almost as important as
Salmonflies, but they don't have the same following. This is
largely because Salmonflies all hatch in one push while Golden Stones
have an initial moderate emergence at about the same time as the
Salmonflies but continue to hatch sporadically for perhaps six weeks in
some locations. Arguably, this makes them more important to the
trout.
Good patterns for the Golden Stone emergence match those for the Salmonfly except in size and color, with golden-tan patterns in size-8 or 10 the best dry options and Matt's Golden Stone the best nymph. My favorite dries are Gould's Half Down Golden and the Golden Yellowstone X. Attractor/terrestrial patterns like Yellow Stimulators and Turck's Tarantulas also match this fly to a degree. Indeed, many popular hopper patterns probably owe as much of their success to matching Golden Stones as to matching grasshoppers. One difference between Golden Stones and Salmonflies in our area is that Golden Stones thrive in the Gibbon Canyon, while there are only a handful of Salmonflies there. |
| Yellow Sally | Isoperla sp. and Suwallia pallidula | Yellow Sallies are a size-14 or 16, making them the midgets of the summer stoneflies. They hatch to a degree from almost all streams in our area, including small meadow streams like Soda Butte Creek, which otherwise lack significant stonefly populations. Like Golden Stones, they typically last six weeks or so in varying numbers. Though Sallies are not a marquee hatch, trout will sometimes key on them, even when Salmonflies or large mayflies are present, so it's always a good idea to carry some. To imitate non egg-layers, a small Yellow Stimulator is as good as anything else. For the egg-layers, a small Elk Hair Hopper works well in fast water because it floats well, while in slower water a dedicated Sally pattern such as the Goldie Hawn is a better choice. |
| Olive Stone | unknown | All you need to know about this fly is that it hatches in the Gibbon Canyon for about a week in mid-June, where it is best imitated by an Olive Stimulator in size-12 or 14. |
| Medium Black Stone | unknown | This insect hatches about the same time as the Salmonflies. It's essentially a curiosity, nothing more. |
| Brown Stone | unknown | A fairly small summer stonefly that stumbles out a few at a time. A Turck's Tarantula imitates it along with 234 other things, which is one reason it's such a good fly. |
| Little Black Stone | unknown | The Little Black Stone may be the first hatch of the year save midges. A small Trude is probably close enough, or a Black Caddis |
| Medium Yellow Stone | unknown | As noted above, this fly may or may not be different than a Yellow Sally. A #14 Yellow Stimulator matches it, versus a #16 for the definite Sallies. |
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Contact Information |
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| Phone: | (406) 848-7314 |
| Address: |
PO Box 196 202 Second Street South (US-89) Gardiner, MT 59030 |
