Conker's first use of the Flamethrower might be at the Nasty/Nice sign in Windy. This is if he remains idle there for long, causing him to eventually be annoyed with the butterflies, and he burns some with it.
The Flamethrower is later used as a context-sensitive item in both the Barn Boys and Bats Tower chapters. In both cases, Conker has to balance and walk across narrow paths, where Bats see and then swoop at him. Conker has to use the Flamethrower on each one that gets close to him. Doing so ignites the Bat and kills it.
- Conker's Bad Fur Day: The Official Nintendo Player's Guide, page 42