For the dry fly-fisherman who enjoys the warm days of early summer when hatches are prominent and the fish rise steadily, winter can be a long dreary experience. Happily, the Lower Yuba River can make those winter days fly by with good fishing and plenty of hatches to keep things interesting. This is the chronicle of one of those hatches.

Over the past few years, western anglers have begun to awaken to the presence of an early hatch of medium sized stoneflies. The Skwala stoneflies do not cover a wide area of California but thankfully the Lower Yuba River has a substantial population as does the Truckee area.

The Skwala Stonefly is similar in appearance to the golden stone of early spring and summer but is smaller than the golden. The abdomen is a dirty yellow with a slight olive tinge. Also, the wings are dark gray unlike the golden stone’s light brown. Like all stoneflies, the Skwala nymph prefers fast moving, well aerated, cold, clear water with a rock and cobble bottom. They become more active as the water temperature begins to pass 45 degrees. The emergence on the Lower Yuba can begin as early as late December but usually doesn’t get started in earnest until early January. You can fish Skwala patterns into mid-April before the fish begin to lose their interest!

Skwala Adult (top view)

The emergence begins as the nymphs start moving towards the banks. They are, as are most stoneflies, poor swimmers once they are dislodged from the bottom, which happens frequently as they migrate. Fish will look for them in the drift along the banks. Any golden stone nymph imitation in size #8-#10 will work as a searching pattern. However, be carefully that you are not wading where you should be fishing.  If you are interested in seeing the nymphs, you can overturn a few rocks at the water’s edge. When the migration is in full swing, there should be plenty of them for you to view.

Skwala Adult (bottom view)

Nymph fishing is best done with a two fly indicator system. The top fly is a stone nymph imitation with a small mayfly or caddis pupa dropper hung 12 inches either off the eye or bend of the top nymph. I will normally tie in a five inch piece of 4x monofilament to the end of a nine foot 4X tapered leader. The split shot are attached above the knot. The knot will stop the split shot from sliding down to the fly. You will need enough lead to get your fly to the bottom. The dropper monofilament can be either 4 or 5x.

The adults are best imitated by a Stimulator type pattern in size #10 3x long. Early in the emergence a bushy pattern will work but, as the hatch progresses, it is important that your imitation sits low in the surface film. If you watch the female adult on the water, you will see that she looks like a black stick with moving legs. The low riding artificial should include the female’s prominent black egg sack. The hackle on the adult pattern below has been cut on the bottom to allow the imitation to settle into the surface film.

Low riding Dry Fly Pattern

There are a few things to remember when you are fishing a dry adult pattern. The adults hide out in the streamside willows and brush during the coldest part of the day. The egg-laying flights don’t start until the temperatures are warm enough for the females to fly. This normally happens in the early afternoon. By fishing a dry fly alongside the willows and brush in the warmest part of the day, you will be fishing effectively. You can tell when the fish begin to feed on the females. The rise is an explosion, especially early in the emergence. Later in the emergence the rises will not be as explosive but will be heavy swirls. As there can be several different insects beside the Skwala stoneflies hatching during late January through April, you will need to watch the rises to be able to identify whether the fish are feeding on stoneflies, caddis or mayflies.

While we are on the subject of the adult, it might be well to mention that the Rocky Mountain area has a hatch of Skwala stone flies. However, these bugs are a different genus and are olive in color. The Skwala stone flies of the Lower Yuba and the Truckee are predominately yellow with only a tinge of olive. In my opinion, many of the patterns that appear in the fly shops are Rocky Mountain based and are much too olive. I normally tie my adult patterns with olive thread which lets the olive color bleed slightly through the yellow dubbing.

Although the Lower Yuba is a year around fishery with great early March Brown, Pale Morning Dun, Baetis and caddis hatches, I look forward to the Skwala emergence to begin brightening up my dreary winter!

This entry was posted Friday, October 9th, 2009 at 4:25 pm and is filed under Articles. You can leave a response, or trackback from your own site.