I will be spending a week in Yellowstone National Park at the end of August. I don't do a lot of trout fishing, being more of a warm water fisherman. I want to start tying and accumulating flies for the trip. I've tied up some hare's ear and prince nymphs along with some hoppers and beetles in various sizes. I have plenty of wooly buggers and other streamers.

Anything that I have read about this subject has indicated that I need a big assortment of dry flies since there are so many types of bugs in Yellowstone waters. Can anyone give an idea of how to narrow down a reasonable assortment of flies to take there?