Spirit River Squirmy Worms. The squirmy worm very well could be the greatest single fly for catching fish that has ever been created. I know for a fact that two of the greatest fly fisherman that I have ever personally seen on the water, who are members of Team USA World Team, use this fly a ton and have told me that this is one of their very top performers.The squirmy worm fly just simply tears fish up.It is a MUST HAVE in your fly box but do keep in mind, to not ever use glue on this fly and never leave them in your vehicle or boat sitting in the hot sun (they will melt).