Trout are always searching for food. Most of what they eat is small, and almost everything they eat is subsurface. Your fly fishing stream tactics should reflect this: go tiny whenever you can.
Occasionally, I am still astounded by what trout actually eat. In the summertime, in countless freestone streams in Colorado, you may pull a stick out of the river bottom and see mayfly nymphs, caddis larvae, and an occasional stonefly. What you are bound to see is a litter of midge larvae. These tasty little treats are abundant year-round, and patterns that imitate them take fish daily.
Step Back a Moment
It’s sometimes difficult to put a rod down and turn a few stones or even get out a small seine net. A common mistake of the casual rock-turner is to focus on the largest bug instead of the most abundant. If we are to think like a fish (whose brains are as big as their eggs), we must frequently imitate what they see most often. Pull out those #22s and those “cheater” flip downs (thanks, Fly Fishing Forum, for the awesome turtleneck shot).
Between Blue Wing Olives (and other small mayfly nymphs) and midge larvae, we have little reason to ignore the “no-see-’em” box. Yes, you can still lead with a monster bead-head stonefly or worm pattern with a bunch of weight, but make sure you trail something smaller than you are comfortable with. I have been testing my theory of bug size on the fantastic Eagle River this month (June), when the high water has been dirtying up the river and scrubbing the bottom clean for great bug and fish habitat. When the visibility was between 1 and 2 feet, the fish still seemed to see the littlest bugs, and I found trout with those tiny bugs in the corner of their mouths more often than my heavier lead flies.
The Proof
The picture below was from fish #5 of a recent trip to somewhere mid-valley on the Eagle. How many browns and rainbows took the worm? One out of those five. The swimmer in the net (you can just see his tail) took the BWO emerger like it was going out of style. I am convinced that having a little bit of flash gets their attention, but the tiny bug is most often sipped.
So, fill up your midge box, get your turtleneck on (or perhaps a Buff or unique MA-logo bamboo Free Fly sun shield), and watch that indicator like a hawk. Midges and size 20 mayflies get sipped like champagne, not guzzled like beer. I recommend these patterns as my top 5 small bugs:
Barr’s flashback BWO emerger (#20-22)
Olive or purple Juju Baetis (#22)
Soft hackle PT (#20)
Gray, black, or olive Biot emerger (#22-#24)
Good ol’ zebra midges (#20-24)