Use Nymphs. Like Mark said, most Stones crawl out of the water to hatch. They are available to trout 95% of their life cycle as a nymph & only shortly as an adult... I usually carry a few Stone flies nymphs in various sizes , Prince Nymphs are good & I have good luck with the pattern pictured below... For dries I like deer hair Caddis in different shades, mostly dark & for those larger stoneflies I use Stimulators.....
Here's a site that has a lot of stoneflies to look at so check it out.
I tie my nymphs weighted . I use lead substitute wire wrapped around the hook shank to just before the bend & then a second wrap of lead over where the thorax will be... I overwrap the lead with thread & flatten the wire with pliers, coat with head cement & let dry. This gives a good form for the dubbed body because most of the stonefly nymphs I've seen have a flattened body.