San Juan Worm
Some people consider this a controversial fly, mostly because it has the word "worm" in its name. Don Bryant, a Westfly user who has fished New Mexico's San Juan River for 25 years, says of this fly: "The nymph pattern was first developed on the San Juan River below Navajo Dam in NW New Mexico to imitatethe river's large population of aquatic worms. They are generally one inch to two inches long and live in the riverbed itself. They turn up in great numbers if you seine the bottom by turning over rocks or stirring up the muck with your wader boot. They look very much like earthworms or miniature nightcrawlers (some even having the distinctive collar). They come in a variety of mostly neutral colors. The trout feed on them extensively and find flamboyant colors an added attraction. The trout definitely take the SJW fly pattern to be exactly what it is designed to represent, the worms of the San Juan."
How to Fish