Salmonflies on the Big Hole River!

One of last year’s salmonflies taking a rest on the tailgate of my truck.

Right about now, bugs are moving, and if the bugs are moving, so are the trout.

 Yes, it’s time for the salmonfly hatch, that annual rite of early summer, when giant stonefly nymphs, with the imposing scientific name of Pteronarcys californica, approach adulthood and move towards river shorelines. If the trout don’t pick them off along their migration, the stoneflies crawl out on shore and find something, such as shoreline willows or tall grasses and crawl up the plant.

Under cover of darkness, the adult stonefly crawls from its exoskeleton and emerges, at daylight, in all its glory as an adult flying insect. This isn’t a little bug. It’s a seriously big insect that attracts the attention of anglers, and, optimistically, big trout.

While the salmonfly spends most of its life along a river’s bottom, happily munching on old leaves and other small woody debris, it’s the salmonfly’s last few days of its life that create the legends. In the manner of all living things, the adult salmonflies seek out bugs of the opposite sex, and after mating, the females fly out on the river to deliver fertilized eggs to the water’s surface, and thus completes the stonefly’s life cycle and starts the next generation’s cycle.

Not all the stoneflies live that long. They lose their grip on shoreline vegetation and fall in the water, giving an opportunistic trout a quick bite of protein. Birds pick them off tree limbs and in the air. Nevertheless, enough adults live long enough to complete their mission to propagate the species.

Our area’s premier trout stream, the Big Hole River, should be the place to be in this coming week or so.

 Miners’ Union Day, June 13, is when the salmonfly hatch is supposed to happen on the Big Hole, but it’s not something you can depend on. During the years I’ve fished the river, I’ve seen salmonflies as early as Memorial Day and as late as the 4th of July. I’m not an expert but it strikes me that the giant stoneflies emerge a bit earlier in years with lower snowpack in the mountains, and that describes 2021. So, don’t be surprised if the big bugs are already buzzing around now or in the next couple days.

 Now, a big question, whenever the topic is salmonflies, is what is happening with these giant stoneflies?

If you get some long-time Big Hole anglers or residents talking, many will assert that there aren’t as many salmonflies as there used to be. I recall one Big Hole rancher, now long gone, who said the chickens would eat so many salmonflies their egg yolks would turn bright orange. Another old friend, also departed, told of taking the family for a picnic on the river, and within minutes, the children were running and screaming back to the car because of all the salmonflies.

Salmonflies are totally harmless. Like the cicadas in the East, adult stoneflies have just one mission in their brief moments in the sun, and it isn’t eating. They don’t bite. They don’t sting. Still, when a salmonfly unexpectedly lands on your neck it catches your attention.

 The trouble with anecdotes about swarms of salmonflies is that it’s just anecdotes. If there have been any long-term aquatic entomology studies of Pteronarcys california on the Big Hole with scientific data of counts, I’m not aware of it, and FWP fisheries biologist Jim Olsen commented on that during a presentation to the George Grant Chapter of Trout Unlimited last month.

 Still, I can’t dispute stories about the “good old days,” of salmonfly hatches. My historical memory of happenings on the Big Hole goes back over 30 years, but that’s the blink of an eye in comparison to some peoples’ memories.

I’ve had fun while fishing the salmonfly hatch, though I’ve never had a day when the big trout went bonkers over the big bugs. The hatch also brings high boat traffic, both residents and guides, with anglers pounding the banks, while the trout lay low.

 It’s really kind of a carnival, though carnivals are usually fun.

 Paul Vang’s new book, “Golden Years, Golden Hours,” is available at How Novel, The Second Edition, Isle of Books & Books, or online at

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