Natural insects like ants & bees can be food for trout. Imitation fishing flies are available for many insects for the brown & rainbow trout fisherman. Terrestrial insects are any fish food that has no aquatic stage like grasshoppers, ants, crickets, beetles, caterpillars, spiders and snails, all of which are loved by Trout!
Fly Fishing Techniques for Terrestrial Fly Patterns
When using terrestrials you need to be aware of the movement of the natural insect that you are trying to imitate. It may be a grasshopper that will twitch or it may be a beetle or ant which falls on the water and simply drowns. Use a floating flyline with a tapered leader or try an Umpqua Red Hot Leader with its rifle sight for presentation making the fly land gently on the water. Most of the time the naturals will just blow onto the water so fish where the natural insect would land, it is no user casting into the middle of a stillwater if the natural grasshoppers or ants are landing at the edge of the water.