4. Give the fish something they don't expect.
Sometimes you can't match the insect the trout are eating. Other times, the hatch is so prolific that your fly is lost among the thousands of naturals on the water. You can solve this problem by tying on something that does not attempt to match the hatch, but that looks edible and familiar nonetheless. Terrestrial patterns often work. During a frustrating hatch, try a beetle, ant, cricket, grasshopper, inchworm, or cicada (depending on what the trout are accustomed to seeing). Sometimes a big Woolly Bugger dragged past the nose of a mayfly-sipping trout will bring a violent strike.