Emerger flies represent the stage between nymph and dry fly. A good method to use the emerger trout flies is to fish it under a dry fly approximately 18 inches will do the trick and the dry fly actually work as an indicator. There are many emerger flies around, in fact as they get adapted more and more seem to appear in fishing magazines each year. Emerger Flies are designed to resemble the not quite mature hatching aquatic insect as it leaving the water to become an adult insect. Emerger flies are generally considered freshwater trout flies.