THE GREAT OUTDOORS — This time each year, fly angler’s ears perk up as stories of salmonflies (giant stoneflies) start to spew forth in Rocky Mountain fly shops.
Wide-eyed storytellers talk about the hatch (the emergence of aquatic insects) with enthusiasm, and often, half-truths, while listeners marvel at these stories hoping to glean the secret information and whereabouts to pursue their own salmonfly experiences.
Finding the giant stonefly (pteronarcys californica) to utilize in fly fishing is a hit-and-miss proposition because timing and conditions are everything. When the weather and runoff are good and the fly fisher is in the right place at the right time, epic experiences and stories are produced.
While most fly fishers look to the fabled waters and hatches like those found on the Henry’s Fork and South Fork of the Snake Rivers in Idaho and the Big Hole and Madison Rivers in Montana, Utah has a few rivers with stonefly hatches as well. These waters may not be as well known or produce the size of fish found in those other rivers, but they do provide fun fly fishing opportunities to use large stonefly imitations in both the nymph (an immature aquatic insect living on the stream bottom) and the adult imitation, which emerges from the river and crawls on streamside rocks and willows.
Large stoneflies are typically found hatching in the Blacksmith Fork near Hyrum, the south fork of the Ogden River above Huntsville and the Ogden River below Pineview Reservoir and the Provo River system below Jordanelle and Deer Creek reservoirs. Anglers who like even smaller waters can find hatches on East Canyon Creek near Morgan and the east fork of the Little Bear near Avon, Cache County.
When to look for stonefly hatches
Most anglers looking to fish a stonefly hatch in Idaho and Montana will find hatching insects from the middle of May into June and early July.
On Utah rivers and streams, the bugs will hatch anytime from early May in dry, hot years to late May and into June on wet, colder years.
Numerous stonefly nymph and adult patterns have been created. When conditions are right and the trout are seeing and keying in on the natural insects, most fly imitations that capture the size, color and silhouette of the natural stonefly will produce good fishing.
The stonefly secret
Fly fishers either hate or love the stonefly hatch based on their experiences. A couple of secrets about the stonefly hatch that is often missed by many anglers is the fact that trout will still hit a stonefly pattern for weeks after the natural bugs have disappeared.
In fact, sometimes during the actual hatch, the trout will be so full of stonefly adults that they may stop eating them aggressively. Also, stonefly nymphs are found on the stream bottom rocks in various stages of development and nymph patterns are typically fished successfully year-round on waters that have open regulations.
The higher than normal runoff this year will make fishing the stonefly hatch a bit difficult. With a little study and watching for the exact time that the runoff subsides, fly fishers may still have the opportunity to catch a trout or two on stonefly patterns.