Bass are opportunistic feeders, and many subsurface bass flies will work when fly fishing for bass. While we do “match the hatch” even for bass in trying to imitate what they are feeding on, like crayfish and different baitfish species, subsurface bass flies often are taken because bass strike reflexively. Pay attention when you catch the first fish of the day. Try to replicate how you caught the fish and try to develop a pattern. If you find a pattern that works stay with it but keep in mind things change and be ready to change with the fish.
Imitation of bottom-dwelling prey such as crayfish or leeches and different baitfish with smallmouth bass subsurface flies will help you have success and catch more smallies. When imitating crayfish, use a weighted crayfish imitation such as Pat Ehlers’ Long Strip Crayfish for fly fishing smallmouth bass and use a varied strip and twitch tactics to tease bass into eating.
Largemouth bass, like smallmouth bass, can be very opportunistic feeders. Streamers such as a Pat Ehlers’ Sunfish imitation fly are a good choice, as sunfish are a big part of a largemouth’s diet. Cast and retrieve a Clouser Minnow and fish it like a conventional jig. The Clouser Minnow is one of the most effective flies ever created.
Like the smallmouth bass, largemouth rely on crayfish as a primary food source. An impressionistic imitation crayfish fly such as the Ball Peen Craw is a great choice to fool largemouth bass with a fly.