Western Stoneflies
Yellow Sally
The most prolific stonefly on Western waters—and possibly the most overlooked—is the Yellow Sally or Little Yellow Stonefly (Isoperla species). Many anglers don’t recognize this hatch when it is occurring right before their eyes, or don’t carry flies to imitate nymphs and adults in the correct places and seasons.
Yellow Sally nymphs are a mottled light brown or tan color (7-18mm). The adults are substantially lighter colored, from pale yellow to fluorescent yellow or even lime green.
Yellow Sallies thrive in tailwaters, spring creeks, and freestone streams. My home waters in Colorado—the South Platte, Blue, Colorado, Gunnison, Arkansas, and Roaring Fork rivers, to name only a few—have excellent Yellow Sally hatches. Colorado guides know that Yellow Sallies provide some of the most dependable stonefly fishing of the year.
A nymph imitation such as a #12-14 Oliver Edwards Yellow Sally is my go-to fly between late June and the end of July. I typically add a #18 Beadhead Pheasant Tail, #16-18 Barr Emerger, or #12-14 Hare’s Ear to my nymph rig to imitate the Pale Morning Dun and Green Drake mayflies that generally hatch at the same time.
Splashy rises along the streambanks often signal fish eating Yellow Sallies, and if I spot a fish lying in a feeding position along the bank, I show it a yellow Stimulator or Headlight Sally (#12-14) as a first choice.
Terminal Tackle
It’s difficult to make generalizations about tackle for all stonefly fishing, since Salmonflies require heavy, weighted nymphs and large wind-
resistant flies, while Yellow Sallies are more delicate.
To cover all these situations—and to meet the demands of large Western rivers and frequently windy conditions—use 9-foot, 4- to 6-weight, fast-action rods.
When fishing smaller stoneflies (#10-14), I typically use a 4-weight rod, but when I need to lob a heavily weighted Kaufmann’s Stone nymph or punch a Rogue Stone dry into a stiff breeze, I use a 6-weight.
My basic stonefly nymph rig is a 9-foot leader terminating in 2X to 5X tippet, depending on fly size. Use the thickest tippet you can get away with—trout are not typically leader-shy with stonefly imitations. Water clarity is also a consideration—use finer tippets in clear water and fluorocarbon tippets and leaders for nymphing.
For drys, use 9-foot monofilament leaders, tapering to 3X or 4X, depending on the wind and water conditions and the size of the fly. Longer leaders are normally not required because, especially in fast water, trout either jump on stoneflies or they don’t. And with large flies, a long leader can be difficult to turn over.
Nymphing Tactics
The most productive method of fishing stonefly nymphs is on the dead-drift with a conventional two-fly rig. Carry both weighted and unweighted nymphs to fish a wide array of
structure transitional zones such as midchannel shelves to deeper slots and highly oxygenated pocketwater. The unweighted nymphs fish best in shallow riffles and near the banks.
Stonefly time often coincides with higher flows in the spring, and runoff can cause water clarity issues. Under these conditions, wading anglers should use a straight upstream delivery along the bank. Carefully managing the fly line under your index finger is the best tactic. Strip the fly line as it floats back downstream to alleviate any drag that might arise due to poor line control.
The upstream delivery also reduces the chances of spooking trout sitting in shallow riffles. In theory, trout can’t see you because you’re casting from their blind spot.
The edges of the stream are the first places to clear during spring spates and, in search of big bites, opportunistic trout often occupy these areas. The food outweighs the risk, and they position themselves in just enough water to cover their backs. Work the bankside water carefully and thoroughly, then take a step or two upstream and repeat the process.
In short, don’t ignore skinny water you think is too shallow. Twelve to 18 inches deep is plenty for a trout feeding on stoneflies.
Dry Flies
fishing adult stonefly imitations is one of the most rewarding experiences in fly fishing. Trout feeding voraciously on adults sometimes create splashy rises. At other times, trout in slower water slurp stoneflies slowly and confidently as if they were feeding on drifting mayfly duns. This usually occurs when stoneflies are drifting helplessly on the surface of the river, as opposed to fluttering females depositing eggs.
It’s not uncommon to see caddis, mayflies, and craneflies hatching at the same time as stoneflies, which can further complicate things with regard to fly selection.
Careful observation of the naturals should help resolve any doubt about what trout are actually feeding on. Sometimes trout feeding on mayfly duns can’t resist the appearance of an easy, large stonefly meal. Don’t be afraid to experiment.
If you see a fish rising, cast to it (of course), but adult stonefly imitations are also excellent for covering likely water. Fish methodically, showing your fly to as many trout as possible, and if stoneflies are around, you will find willing eaters.
Pay close attention to darker areas in the substrate where trout like to hide, and focus on bankside water with logs, canyon walls, and partially submerged boulders where stoneflies may fall into the water.
Both dead-drifted and skated presentations are effective with stonefly drys, but try to twitch your pattern rather than skating it smoothly through an entire swing. This produces a lifelike fluttering behavior common in egg-laying females and often triggers explosive takes.
With large drys, don’t set the hook too soon. Allow the trout to eat your fly and dip below the surface before you set. If you can still see your fly, it’s too early to set the hook.
Dry/Droppers
As the high-water season recedes, many previously hard-to-reach spots become accessible for targeting opportunistic trout. This post-runoff period is perfect for dry/dropper fishing with two stonefly imitations, or a stonefly dry indicator and a mayfly nymph dropper.
One of my favorite rigs is a #8-10 Amy’s Ant dry with a #18-20 Mercer’s Tungsten Micro May or a #12-14 Oliver Edwards Yellow Sally nymph. In effect, your dry becomes your strike indicator, suspending one or two nymphs below it.
During a time when discriminating trout become suspicious of standard two-fly nymphing rigs in deeper water, use the dry/dropper rig to cover a wide assortment of water, including transition zones that funnel into deep pools, riffles, runs, pocketwater, bankwater, and protruding logs. This rig is especially productive in skinny water that rarely gets fished with conventional nymph rigs.
Big Fish
While stonefly hatches are not as prolific as mayfly and caddis hatches, they provide some of the best big-fish opportunities of the year. Timing may require several visits to each watershed, but once you hit the hatch right, you’ll never forget the experience.
Pat Dorsey is Fly Fisherman’s Southwest field editor and author of Fly Fishing Western Tailwaters (Stackpole Books), due to be released in September 2009.
Copyright © 2012 Intermedia Outdoors
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