Written by Mike Lawson
The giant stonefly, Pteronarcys californica, commonly called the Salmonfly, usually takes center spotlight when stoneflies are concerned. There’s no question that this giant aquatic insect has a well earned reputation for bringing huge trout to the surface. Some of the largest trout I have ever hooked were with mammoth sized dry flies when the Salmonfly hatch was on. I’m lucky; as I live only a few hundred yards from the Henry’s Fork. When it’s time, usually about the 20th of May, I can keep trying until I hit the right day. But with Salmonflies, it’s either feast or famine. The most consistent fishing happens when the huge nymphs are starting to concentrate near the banks. During that time the trout really load up on them. By the time the adults emerge the trout are ready for a tablespoon of Pepto Bismol because they’re so full of nymphs they’re ready to pop. It usually takes several days for their indigestion to subside before they’re ready to eat again. You usually get a day or two of hot dry fly fishing before the Salmonfly hatch is over and done.
The Golden Stone, a slightly smaller cousin of the Salmonfly, offers much more consistent fishing. The emergence period for these size 8 and 10 stoneflies spreads over 3 to 6 weeks instead of the 4 or 5 day period common with Salmonflies. The trout see just enough of them to stay interested, but they don’t get enough to keep their bellies full. As long as there are a few Golden Stones around the trout will be looking for them. Some of the best Golden Stone fishing can be in early July, a full month after the first days of the emergence.
Golden Stones prefer a wider variety of habitat than their larger cousins. They start coming out a few days after the Salmonflies in areas like the Box Canyon, Riverside, Mesa Falls, and other oxygen rich sections of the Henry’s Fork where Salmonflies thrive. Further downstream on the Henry’s Fork the Salmonfly population thins down but not Golden Stones. Their numbers stay strong well downstream of St. Anthony. They are also common on several of the tributary streams to the Henry’s Fork including Warm River, Fall River and the Teton River.
Good Golden Stone fishing also happens on the South Fork of the Snake and the Madison in Montana. On those streams it comes off closer to the first of July, a few weeks later than the Henry’s Fork. There is also a species of the Golden Stone, commonly called the Summer Stone that happens on the South Fork in August and early September. The wings of the males are under developed and they can’t fly so they scurry over the gravel bars with their powerful legs in search of a mate. They can also scamper over the water. These stoneflies are nocturnal offering some of the best dry fly fishing on the planet in the early morning hours before the sun comes up.
Smaller stoneflies like the Yellow Sally and Little Green Stone usually get lost under the cover of better known hatches like the Pale Morning Dun, Green Drake and other mayflies and caddisflies. Yet I have had some memorable days using imitations of these stoneflies when the trout would not look at a well presented mayfly pattern. Smaller stoneflies are especially significant on the Madison and South Fork of the Snake.
With the Madison and South Fork just turning on, the best stonefly fishing is still in front of us. We’ve got some great new patterns in the shop including the Henry’s Fork Foam Stone and Dornan’s Water Walker, as well as the some old reliables including the Rogue Stone, Chubby Chernobyl, Berrett’s Mutant Stone, and my own Lawson’s Yellow Sally.