A few summers ago I was fishing the streams of Northern California - the Upper Sac, McCloud and Pit - and purchased a few local flies from one of the Redding fly shops. One of the patterns was a Yellow Sally imitation designed by Mike Mercer, using small beads for the abdomen, a synthetic wing and yellow hackle. The beads were bright yellow, with the last bead being orange to imitate the egg sac of the female. The fly worked great, but soon I lost the two I had.
That evening, not having any beads to tie Mercer's pattern, I tied up a yellow stimulator and eliminated the tail and instead dubbed a bright orange fur ball for the egg sac. The next day, I fished the fly, and it too, worked great. Since then, I have used this fly with success both out west, and on Eastern streams during the summer months. The stoneflies drop their eggs in fast water and riffles on the edges of slower deep pockets and eddies, and that is where this fly excels.
The pattern itself has some interesting history, too, as to who actually came up with the pattern. Check it out here, on the Orvis News blog - Orvis News Yellow Sally.
Tie some up and fish them with confidence during the day or evening. Thanks again to Tim Flagler for the great video production.
Sharpen your hooks, and check the water temperature before wetting a line - if it's over 68 degrees F, let the fish be.