Editor’s note: The following is experpted from TU’s book, “Trout Tips,” available for overnight shipping.
It’s hard not to like tandem rigs—two flies working together for the single purpose of making you happy. But there should always be rationale for the pairing. Sometimes that’s merely to help you see better. I can’t always see a size 20 Blue-winged Olive, so I put a highly visible size 14 H&L Variant just above it. If I see a rise or a splash near the H&L, I assume the BWO got bit, and set the hook.
The tandem can also cover two stages of an insect. For example, the adult dry fly can lead the emerger and serve as a strike indicator in the process. Hard to beat a size 16 Parachute Adams with a size 18 Barr Emerger or RS2 below it. The important thing is to have rational for every tandem rig you present. Variety for the sake of variety is not always a good thing. If you think you’re covering your bases by matching two flies that don’t reasonably work together … well, you are not.
— Kirk Deeter