I came to dropper flies the way I typically come to any so-called new development in flyfishing.That is, several years late and only after half a dozen good fishermen told me they worked like a charm,especially on trout eating tiny insects coming off the water in late summer.
Several of those fishermen were guides,whose endorsements can usually be trusted.Guides spend more time on the water than the rest of us,often with clients who are less than experts, and the best of them are ruthless about weeding out tackle and techniques that aren't easy and effective.
The practice of tying two flies to one leader has actually been around for well over a century but came back into fashion a decade or so ago.Originally,dropper referred to the top fly because it was "dropped"directly off the main leader on its own short piece of line. Today,the order is reversed,and dropper flies are tied on an 18- to 24-inch section of smaller-diameter tippet attached to the bend of the first fly's hook with an improved clinch knot.
Although the combinations of flies you can use are almost infinite,typically the first fly is a large dry,and the dropper is something that sinks or is too small to be seen on the surface.The large fly acts as a strike indicator for this second fly.
"Fly locator"may be a better description than strike indicator,though.Sometimes your top fly will sink like a bobber when a fish takes the dropper,but if the short section of leader between the two flies isn't drawn up tight he can spit it out again without ever disturbing your indicator.That's why it's a good idea to set the hook whenever you see a rise or boil near your top fly.
It was this last aspect that the guides had in mind when they resurrected the technique. Clients could more easily fish small,hard-to-see patterns if they hung behind larger,more visible dry flies,and enjoyed the added advantage of having two hooks in the water instead of one.
Casting two flies at once isn't as hard as it sounds. Just use a slightly slower casting stroke,which will open up your loop a little (a tight loop is more likely to foul up when you're using a dropper). And fishing them is simple, too. I usually use a basic dead drift,unless I'm working a hatch of active insects like caddisflies,in which case adding a twitch or skitter may draw more strikes.
I fish these rigs in Cheesman Canyon on Colorado's South Platte River. This is famously technical water, where large wild trout can get infuriatingly selective to tiny flies.The trout might appear to be taking bluewing olive duns,but they could actually be eating cripples, emergers,floating nymphs,or something else entirely, like spent trico spinners floating flush with the surface. Because the rise forms often look alike,you're sometimes reduced to just trying different patterns until you connect.
I've learned to tie on a large dun as my top fly and leave it there,changing the trailer until I find something that the fish are feeding on. For one thing, at some point trout usually start eating the duns, so I like to have one out there. For another, the white-winged parachute pattern that I favor makes it much easier to fish the flush-floating or slightly sunken fly behind it that's hard enough to see when I'm tying it on,let alone when it's out on the water.
KEEP IT CLEAN
I've always hated to foul-hook fish, and it can happen when you're fishing these rigs. A trout goes for your top fly,and you miss him and then snag him in the belly with your dropper.You can avoid this by making sure that the length of the line between your top and bottom flies is never less than 18 inches.Other fishermen have told me that they need 22 to 24 inches,possibly because they set the hook harder than I do. —JOHN GIERACH