October fly fishing in Montana often produces our biggest trout of the year. Large browns are prepairing to spawn and are much more aggressive than normal. The big trout are also moving upriver and we get several spawning runs of huge trout that run out of lakes such as Canyon Ferry, Ennis and Hebgen into fisheries like the Madison River. October also sees much lighter fishing pressure than any other part of the traditional fishing season: locals are out hunting and tourist season is winding down. The best way to target the big fish is to use the big uglies under the water. Fishing large streamers as nymphs trailed by a smaller baetis emerger is very effective. On cloudy days, stripping large streamers can be very productive. Cloudy and rainy days also produce great dry fly opportunities over prolific baetis hatches. These mayflies are often called blue winged olives and hatch in great abundance on stormy days bringing nearly every trout in the river to the surface.