Two big stoneflies own June on Western freestone rivers, and the hatch charts on this site keep them separate for good reason. The salmonfly, Pteronarcys californica, is the giant: a size 4 to 6 insect with an orange-and-black body, listed on 31 rivers, peaking in a short, intense window that moves upriver over a couple of weeks. The golden stonefly, mostly Hesperoperla pacifica and Calineuria californica, is a size 8 to 12, listed on 65 rivers, and comes a week or two behind the salmonflies and lasts a month or more. If you can only be on the water for one of them, the golden is the safer bet. If you can time the salmonfly, nothing else in trout fishing is quite like it.
Two families, two body clocks
Both are Plecoptera. The salmonfly belongs to the Pteronarcyidae and spends several years, generally cited as three, as a nymph on the bottom of fast, rocky rivers before it crawls out. The golden stones are Perlidae, predatory nymphs with a two-year life on most rivers. A third Perlid, Claassenia sabulosa, the short-winged golden, emerges in late summer and mostly at night, and it is why a golden stone dry still catches fish on the Madison in August.
Neither hatches in the water. Mature nymphs migrate to the banks, crawl out on rocks and logs at night or first light, and split their shucks on dry ground. Empty shucks on the rocks are the surest sign you are in the hatch. Adults live for days, mate in the streamside brush, and the females fly back over the river to drop eggs, which is when they land on the water and get eaten. Wind and clumsy flying put more of them in the river than egg-laying does.
The salmonfly: timing and the rivers here
The salmonfly emergence starts on the lowest, warmest water and moves upstream as the river warms, a few miles a day. The 31 river charts show the geography:
- May: the Logan, the earliest on the site, and May into June on the Deschutes, Henry's Fork, Blacksmith Fork, and Rock Creek.
- June: the Madison, Gallatin, Clark Fork, South Fork Flathead, Snake (WY), the Colorado freestones (Arkansas, Poudre, Eagle, Roaring Fork), the Utah mountain rivers (Bear, Duchesne, Lake Fork, Uinta), and the Northwest rivers (Clearwater, St. Joe, McKenzie, Methow, Wenatchee).
- June into July: the big Montana and Idaho freestones, the Big Hole, Bitterroot, Blackfoot, Yellowstone, South Fork Snake, Salmon, Lochsa, and the North Platte.
The catch is runoff. Salmonflies hatch as the water warms, which on a freestone is often while the river is still high and dirty from snowmelt, and a late, heavy runoff can bury the whole hatch. The dam-controlled rivers (the Deschutes, the Henry's Fork, the South Fork) are more predictable. On a freestone like the Big Hole or Yellowstone, watch the gauge on the river page: the hatch and the fishing come together when the water is dropping and clearing.
The golden stone: the longer, quieter hatch
Goldens peak in June and July on 46 rivers, and June through August on the Montana and Idaho freestones (Big Hole, Bitterroot, Blackfoot, South Fork Flathead, Lochsa, Salmon, South Fork Snake, Snake, St. Joe, Yellowstone, North Platte, New Fork). The Yellowstone Park rivers (Firehole, Gibbon, Lamar) and the Upper Provo get theirs in July and August, and the Deschutes runs May through July. Goldens are also on many rivers that never see a salmonfly: the Colorado, Gunnison, and Taylor in Colorado, the Arizona and New Mexico streams, and the California rivers all list goldens and nothing bigger.
The emergence is less concentrated. There is no cloud of bugs on the willows. But the adults are around for weeks, egg-laying flights happen in the afternoons and evenings, and trout that have learned to look for big bugs along the banks keep looking. On the freestones the golden hatch carries dry-fly fishing from the end of the salmonflies through the start of the hopper season.
Nymphs first
For every day the adults are on the water, there are weeks when the nymphs are crawling toward the banks and trout are stuffed with them. Big nymphs before and during the hatch are the most reliable fishing of the whole event. The river pages list a Golden Stone Nymph and a Kaufmann Stone in 8-10 (the Madison, Big Hole, Deschutes, Gunnison, Teton, Logan, and others), a Rubber Legs on the Firehole, and a Prince Nymph in 10-12 on the Gallatin, Poudre, and Shoshone. A black Kaufmann Stone in size 4 to 6 covers the salmonfly nymph, though no river page lists one by name. Fish them heavy and close to the bank, in the soft water behind rocks and along the inside of bends, where migrating nymphs collect, with the fly bouncing the bottom.
Dry flies from the river pages
| Insect | Patterns listed | Sizes |
|---|---|---|
| Salmonfly | Stimulator (orange), Chubby Chernobyl, Sofa Pillow and Improved Sofa Pillow, Clark's Stone | 4 to 8 |
| Golden stone | Yellow Stimulator, Golden Stone Dry, Royal Wulff, Chubby Chernobyl | 8 to 12 |
The Yellow Stimulator in 8-12 is listed on more than 60 of the golden-stone rivers, and the Stimulator in orange in 4-8 on nearly every salmonfly river. The Chubby Chernobyl covers both with a color change and floats a dropper. Fish the dry tight to the bank, under overhanging brush, and in the seams below the thickest willows. Slap it down; a stonefly hits the water hard. Twitch it. Let it drag at the end. The fish are used to a big bug that moves.
Finding the hatch
Drive the river. On a salmonfly river the hatch is somewhere on it for two or three weeks, but only in one place on any given day, and the best fishing is usually a few miles above the thickest bugs, where the fish have seen a few and not yet been pounded. Look for shucks on the rocks, adults in the willows, and birds working the banks. If the fish are full and refusing, move upstream to the front edge. Bring 2X or 3X; a size 4 dry on 4X twists the leader and a big brown in fast water breaks it. And check the state fish and game agency, because several of these freestones have float and access rules that matter in June.