Woolly Worm Yellow - Worm. Another variation of the wonderful Woolly Worm fly collection is the Yellow Woolly Worm, fishable in all types of water conditions regardless of time of day, type of water, temperature or colouration this fly can handle even the toughest situations. This fly is the benchmark to all buggers and leeches, and the results it provides demonstrates this entirely. The Wooly Worm Yellow can be used to catch every freshwater fish imaginable, going from pan fish like the blue gill and small and large mouth bass, to carp and catfish, and obviously trout and salmon absolutely adore this fly.