Yeah Jack; it’s a great site. I think it was you that originally turned me on to it.
Ian,
It’s worth tying a few early brown and black stone dries and keeping them in your box. Since stoneflies hatch/transform on land dries are not always that effective. During egg-laying though, the fish may get on them. IMO, the biggest problem with the early stones is they hatch when the water temp is very low and the fish usually aren’t too active, and there never seems to be many on the surface to interest the trout enough to rise.
With respect to stoneflies, what are really worth the space in you box are yellow sallies, the bright green and yellow stones the hatch later in the spring. I’ve had some great days fishing these flies on Penns, both Fishing Creeks, and some Catskill and Pocono streams. I tie them the same way. Splayed tails, dubbed body, flat wing and trimmed hackle. I use a translucent “Fly Film” wing, color it with a pen, and use some a little deer hair as an underwing.
The bigger stones are best imitated by a stimmie type fly or an elk hair caddis type fly of the proper color and size. Good luck.