|Image Courtesy Midcurrent.com/Bill Tipton|
This combo works especially good on the creeks I fish, as the beadheads are perfect for attracting subsurface feeding in the riffles & eddies. In this scenario the CDC caddis simply serves as an indicator fly. If it moves unnaturally, fish on!
Should I see trout rising to feed, the dry still maintains an adequate enough drift to attract strikes despite the second fly in tow. It's very convenient that you don't necessarily need to re-rig.
The "hatches" aren't that spectacular on the creeks I frequent, so my ratio is probably 80/20 nymph to dry, but the dries do catch fish and in my opinion are worth adding to the line.
There's a very good article in Midcurrent expanding on dropper flies and tandem rigs HERE. It's a nice primer if you don't fish this style right now.
On a non-fishing note, Lilly & I enjoyed our own form of tandem rig last night. All I heard was "Go faster Daddy, go faster!" Great fun for a 15 minute cruise around the neighborhood.