Worms on a fly rod, Egads Martha, tie the cow to the fence so it doesn't fly away over the moon, What is the world coming to, imitation worms.
Actually, I first saw this fly back in 1981 in Montana when it was tied with either red or flame orange floss with a gold wire rib on a Mustad 37160 hook. then Tltrachenile hit the market and the 'worm' was never the same. It is a damn effective fly at the right time in the right water conditions. There are many a Bighorn River guide who made his/her reputation on the effectiveness of the San Juan Worm.
Just don't tell the bait guys that fly fishers are imitating worms.