A Guide to Dry Fly Fishing Techniques
With a few exceptions, dry flies imitate insects that have fallen onto the water by mistake. The essential thing about such insects is that they are trapped on the water’s surface: they cannot and do not move much on the water.
They drift helplessly in the current until they either drown and sink, or get snapped up by a trout!
Therefore, to successfully fish with a dry fly, you have to allow it to move with the river’s current like a doomed natural insect. And this in turn means that most dry fly fishing in rivers is done by casting the fly directly upstream and letting it drift back toward you in the current.
In lakes, the same concept applies: you cast the dry fly out onto the water and you don’t try to move it. You simply wait for the trout to come to the fly and – hopefully – take it.
Some terrestrial insects end up on the water by design rather than by error. Female mayflies, for example, alight on the water’s surface in order to lay their eggs. Even so, once they are on the water depositing eggs, mayflies still drift with the current like a trapped beetle or cicada.
Female caddis flies also deliberately descend onto the surface of the water to lay eggs.
However, unlike the mayfly, the female caddis fly doesn’t sit on the water and drift with the current.
Instead, she skims across the surface of the water, like a cormorant flying across the sea,
all the while dropping her eggs into the moving stream. And because the female caddis fly skims on the water’s surface like this, she is still an easy meal for a trout prepared to stick its snout up out of the water.
This scenario gives rise to the only form of river dry fly fishing I know where the dry fly is not fished on a dead downstream drift in the current.
When trout are rising to skimming caddis flies, you tie on a special cone-shaped adult caddis imitation, which is made of deer or elk hair.
The design of this fly is such that it skims nicely over the water’s surface.
You then cast this fly out across the river at a right-angle to the bank and allow it to drift down and in toward the bank.
As the current takes hold of the fly line, the fly begins to skim across the surface of the river – just like the real thing.
Then, wham! It’s only a matter of time before one of the rising trout mistakes your artificial fly for a real insect.
Summary: in nearly all dry fly fishing cases, dry flies are fished in the ‘dead-drift’ style – because this is the only way to correctly imitate a stranded terrestrial insect floating along in the current. One of the rare few times this rule does not apply is when using a caddis dry fly, which skims across the surface of the water.