October is a fantastic time to enjoy Montana fly fishing. Water temps are dropping fast as the days get cooler and the fishing can really turn on as the summer tourists have headed back home and kids are back in school. Tom Jenni and I put on for a three day overnight float on the Lower Yellowstone last weekend and only saw 3 other guide boats in 3 days despite averaging 40 trout per boat per day. Although the very beginning of October can still produce some decent hopper and ant fishing, autumn fishing is dominated by the baetis hatch and stripping big streamers. Although making any hard and fast rules in the sport of fly fishing is never a good idea, there are two main strategies I use in October: going big and going small.
The baetis (aka: blue winged olive) is the dominate late season hatch on Southern Montana waters. This dependable small mayfly weighs in at a diminutive size 18 or 2o. Despite is small size its dramatic abundance raises the interest level of even large fish. In October we almost always fish some type of baetis imitation when tossing dries or nymphs. When dry fly fishing a parachute adams is a good bet, but the many versions of baetis dries out there will also work. When nymphing trail your top fly with a beatis nymph or emerging baetis pattern. Browns also become more aggressive in the fall and targeting large pre-spawn migratory fish can produce the largest trout of the season. The best way to catch browns over 20" is to drag big streamers around. Both stripping with a classic streamer retrieve and dead drifting or "tight lining" bunny fur can produce some very big tugs. Although numbers go down when you up the fly size quality definitely increases. October fly fishing offers many options, but to maximize enjoyment try tossing small baetis dries for the best surface action and stripping giant streamers when targeting monsters. Go big or go small!