By no means is 20 the smallest hook size, but it certainly is the gateway to the tiny sizes and a frustrating hurdle for many tiers. Sure, the hook is small and one real good tug on the thread and you could be left with no hook at all. But if approached with a bit of patience and the right tools, anyone can produce effective and elegant patterns at this size. There are some real advantages to tying in the small sizes as well. For many of the tiny bugs, a bit of thread and a well-trimmed wing are all that is necessary to tie fish-fooling flies. Most midge patterns are little more than thread itself. The most effective trico patterns in my box are a single hackle feather and some thread.
In my opinion, one of the simplest dry flies to tie in smaller sizes is a version of the “F Fly.” Though this fly is often tied in more common sizes and can imitate any mayfly or even a slick-water caddis, it works great early season as a Blue Wing Olive pattern in sizes 18 and below. Best of all, it is a simple tie and the basic steps are ones most tiers are familiar with from other patterns. In this video tutorial from Hammer Creek Fly Fishing, a size 14 F Fly is tied, and very little modification from the steps in this video are needed to size it down to the right sizes for our tiny fly trials.
For success with the smaller sizes, first start with quality hooks. The bargain hooks are fine if you’re tying big wooly buggers, but for the small stuff strength matters. the cheap stuff bends in the vise, and in fish jaws. I don’t play with either of those options if I can help it. The right thread is the next step to tying small, and often the part that can be frustrating for the novice tier. Thin threads break often, strong threads are bulky and awkward. Do yourself a favor and get a good thread in a size 8/0. I prefer the UTC for its strength to size ratio. The UTC thread is grippy enough to keep slick CDC feathers in place, and strong enough to cinch materials down tight. Armed with good hooks and good thread, you’re on your way.
When tying in the small sizes, keep your thread tension up and your bobbin close to the work. It will allow you to “grip” materials with the thread close to the hook and keep things in check. Pay attention to your proportions, use a minimum of thread wraps per step, and when it comes time to tie it off, one crisp 4-turn whip finish will do the job. For the F Fly in smaller sizes, feel free to use your preferred body feather, or stick with just the thread if you’d like a smooth, elegant body. All will catch fish. Give the F Fly a try in a smaller size than you’re comfortable with, and not only will you be able to progressively tie smaller versions, but you’ll have a deadly fly at every size.