San Juan Worm Red - Worm. The Red San Juan Worm was first created to imitate the aquatic worms of the San Juan. The living worms tend to be of neutral colors but time and experience have demonstrated that the trout find an added attraction to the extra little coloring. Trout simply cannot resist this tempting imitation when it is put before them. The Red San Juan Worm has a very natural wormlike wiggle to it, fished in busier waters this fly is guaranteed to fool even the most spooky trout.