Fly Patterns - Bill's Little Yellow Stonefly Nymph

               Bill's Little Yellow Stonefly Nymph



During spring and early summer, on your favorite stream you may have noticed small, yellowish bugs flitting about—sometimes in large numbers. If you are fortunate enough to have done so, you may even have seen one of them crawling around on an exposed rock in or near the stream. During evening’s prolific activity, I’ve seen many a flyfisher reach into the fly box and drag out a Light Cahill Parachute to try and match the insects—most always with frustrating results, having mistaken these little critters for mayflies. There are many adult imitations for Little Yellow Stoneflies (aka Yellow Sallies), most of which, to be blunt, are plainly ineffective. They are either too bulky, built on too big a hook, or overdressed with flashy materials that look good to tyers but perform poorly.


Because I’m constantly fishing and guiding on the small streams of the upper Middle Fork American drainage where Little Yellow Stoneflies are prolific, I see them in huge numbers. While I have my own patterns for imitating the adult, I tend to fish the nymph even during a hatch or during the evening egg-laying flights. Sometimes I’ll use an appropriately colored soft-hackle as an emerger imitation, on a tandem rig with the nymph. During this last season, I found some hatching nymphs on exposed rocks. Turning over rocks in the same vicinity, I located some migrating specimens and studied them carefully, comparing them to some imitations in my nymph box. What I found was that my dubbing was the wrong color—not even close—and that my flies were too bulky. The natural was slim-bodied and delicate, with a body color somewhere between light olive and yellow. The wing and abdomen case was dark brown and segmented. Here is an image of a Little Yellow Stonefly nymph:


Now for some technical information, adapted from an excellent article by Rick Haefle, found at:


Entomologists classify Little Yellow Stoneflies as within the genus Isoperla; there are many species within this classification. The nymphs of this group most often occur in areas with a gravel or rocky bottom and moderate to fast currents. They are commonly found in stream drift, making them available and important food items for trout. As they reach maturity, they begin migrating to shoreline areas in preparation for emergence. This further increases the number of drifting nymphs, and it is an excellent time to fish nymphal imitations Emergence usually occurs in typical stonefly fashion: the nymphs crawl out of the water onto shoreline rocks or vegetation where the adult then escapes the nymphal shuck. However, a few species actually emerge in open water in the surface film, just like many mayflies. This is unusual behavior for a stonefly, and drifting emerger patterns become just as important during this activity as during similar mayfly hatches. This point is important to remember when using Little Yellow Stonefly nymphs. After emergence, adults hide on streamside foliage. A quick way to check if adults are present is to simply look on the undersides of leaves of streamside shrubs and trees.


The most obvious and important part of the little yellow stone's life cycle is egg laying. This is when swarms of adults congregate over shallow riffles and runs. After a short flight to gain altitude (10 to 20 feet), egg-laden females set their wings in a shallow "V" and glide gently to the water. As their abdomen breaks the surface tension, a cluster of eggs is released. The females then quickly lift off the water, only to repeat another gliding descent to the surface. Those lucky enough to escape surface-feeding trout will drop five or six times until all eggs have been laid. They then lie spent on the surface where they die. Most egg laying activity occurs in the late afternoon and evening.


My Little Yellow Stonefly Nymph pattern is simple to tie, and made from inexpensive, commonly available materials.


Tying Instructions

1.       Smash the hook barb and place the hook in your vise. Wrap 4 or 5 turns of weight at the thorax area of the hook





2.       Secure the weight in place with thread wraps and a drop of super glue, and run the thread back to the bend of the hook. At that point tie in two biots. The length should be about ½ shank length.

3.       At the same point tie in a thin strip of turkey tail for the abdomen case. Be sure that there is no gap between the biots and the case.

4.       At the same point tie in a piece of gold wire for ribbing.



  1. Dub the abdomen with a taper, larger to the front. End the dubbing at the point where the thorax will begin, which is about one third shank length behind the hook eye. Do not use excessive amounts of dubbing—the body needs to be slender.



6.       Bring the case over the top of the abdomen and tie it off at the front of the abdomen.

7.       Rib the abdomen and case with 4 or 5 turns of the wire.



8.       Tie in a somewhat wider strip of turkey tail for the wing case, at the front of the abdomen. The shiny side of the feather should be down. Be sure that there is no gap between the abdomen and the tied-in wing case.

9.       Prepare and tie in a partridge feather at the same point that the wing case was tied in. See below for tips on preparing the feather and tying it in.

10.   Dub the thorax. It should be somewhat more robust than the abdomen, but still slender in appearance.

11.   Pull the partridge feather over the top of the thorax and sweep the barbules rearward, creating a set of legs. Trim the stem of the feather.

12.   Pull the wing case over the top of the thorax and tie it down just behind the hook eye. This will cause the legs to assume a downward/rearward appearance.

13.   Form a nice small thread head and whip finish the fly. Place a drop of super glue on the head.



Tying Tips

1.    To prepare the partridge feather, strip the fuzzy material from the stem near the bottom of the feather. Leave the stem intact, with about ½” of barbules remaining on the stem. Moisten the feather, and using your tweezers grab its tip and sweep most of the barbules downward. This leaves a small “tab” at the top of the feather. The feather is now prepared for tying in.

2.    Tie the feather in by the tab, with the shiny side down, directly in front of the base of the wing case.

3.    When tying in the biots, don’t try to tie them both in at one time. Tie one in on the far side of the hook, and then tie a second one in on the close side.


When fishing this fly, remember that some (but not all) Little Yellow Stoneflies emerge in the stream flow, and not by crawling to the edge and emerging on rocks or streamside vegetation. Tie up a few of these, and...




Copyright © 2007 - Spring Creek Flycraft and Guide Service - All Rights Reserved