The Woolly Worm may have originated in the Ozarks as a bass fly; however, Don Martinez, a West Yellowstone, Montana fly tier, made the fly popular in the 1950s. It is a very effective fly in both in lakes and rivers, warm and cold. Many species of fish will eat this fly. You can fish this one pattern in different sizes, weights and colors and have good fishing days. It is strongly recommend that beginners to use this fly, although you might get a tired arm from so many catching fish.