Fishing October caddis dries is kinda like fishing hoppers in that you have big fish eating big flies. More subtlety is required, but it offers similar-sized fish on dries.
Not every river gets a great hatch, but an outstanding emergence isn't required. If you see a couple big orange caddis, tie on an orange Stimulator with stout tippet.
I've mostly fished the hatch on the lower Gallatin, but was told by 20-something fly-shop guy that the Gallatin doesn't actually get October caddis (dicosmoecus). Ok, fella. He said that the Gally (as I'm sure he called it) actually got a bug that looked a lot like an October caddis, but wasn't a real October caddis. It does get that bug (see below), but it also gets the real thing.
(cased dicosmoecus larva)You can fish the pupae as well - just a big orange soft hackle should suffice.
If you see the big orange caddis, tie on a Stimmie and hold on tight.