Flies 101: Dry Flies, Nymphs, and Streamers for Beginners

Walk into any fly shop and you will see walls of flies in hundreds of colors, sizes, and shapes. It is overwhelming. The good news is that almost every fly on that wall belongs to one of three families, and each family imitates one kind of food. Learn the three families and you will understand what you are looking at.

Dry Flies: Food on the Surface

A dry fly floats on the surface of the water. It imitates an adult insect sitting on or just above the surface, usually a mayfly, a caddisfly, or a stonefly. It can also imitate a land insect that fell in, like an ant, a beetle, or a grasshopper. Dry flies are made with light, stiff materials that trap air and keep them riding high.

You fish a dry fly when trout are rising, breaking the surface to take insects on top. A rise is easy to spot: a small ring or splash on the surface, often repeated in the same spot. Cast upstream of the rise and let the fly drift down over it, moving at the same speed as the current. If your line pulls the fly faster than the water, the trout will ignore it. A natural drift is everything. The fish gets a long look at your fly, so anything wrong, a dragging drift, a fly that sits too low, a shadow over the water, will put it off.

Nymphs: Food Below the Surface

A nymph imitates the underwater, immature stage of an insect, before it hatches into an adult and reaches the surface. Nymphs drift along the bottom, tumbled by the current, and trout feed on them all day. Trout do much of their feeding below the surface, because that is where most of the food is, most of the time. A nymph is often the most reliable choice, especially when nothing is rising.

You fish a nymph below the surface, usually with a small weight or a weighted fly to get it down near the bottom, and often with a strike indicator, a small float that tells you when a fish takes the fly. The goal is the same: a natural drift, at the speed of the current, near the bottom. A strike can be hard to see, since it happens underwater, so watch the indicator closely. Any pause, dip, or sideways twitch can mean a fish. Nymph fishing is less glamorous than dry fly fishing, and beginners sometimes resist it. Do not. It catches fish on days when nothing is hatching and nothing is rising. It is the workhorse of fly fishing.

Streamers: Food That Swims

A streamer imitates something that swims: a small minnow or baitfish, a leech, or a small crayfish. Streamers are bigger and heavier than dry flies and nymphs, and they are made to move. Instead of drifting passively, you strip a streamer back through the water in short pulls, making it dart and swim the way a small fish would. The motion is what triggers the strike.

Streamers are the fly to reach for when you want to find aggressive fish, especially larger trout. A big trout that ignores a tiny nymph may chase a streamer out of hunger or instinct. It is also a good choice in stained or high water, when a bigger, moving fly is easier for a fish to find. Start with smaller streamers and short casts, and keep your casting stroke smooth.

Sizes and Colors in Plain Terms

Flies come in sizes, and the sizing runs backward from what you might expect. The size is the size of the hook, and a bigger number means a smaller hook. A size 18 fly is small. A size 8 fly is much bigger. For a first box, middle sizes cover the most situations, with a few smaller and a few larger for variety. Getting the category and the drift right matters far more than getting the size perfect.

Color is simpler than it looks. Natural colors, browns, olives, blacks, and tans, match most of what trout actually eat, and they work in most water. Bright colors have their place, especially in stained water, but natural is the safe starting point. A fly that looks roughly like food, drifting naturally, will catch fish. A perfect copy that drags unnaturally will not.

What Goes in a First Fly Box

Start small. A first box needs a few of each family, in a few sizes, and nothing more. Pick a handful of dry flies in common mayfly and caddisfly patterns, plus one or two terrestrial patterns like an ant or a beetle. Pick a handful of nymphs in common patterns, in sizes that cover small to medium. Pick two or three streamers, one dark and one light, in a medium size. That is a working box, and it will handle most days.

Resist the urge to buy dozens of patterns before you have fished the first ones. Fish the patterns you have and notice what works. Add new patterns one at a time, when a day on the water shows you a gap. Your box should grow with your experience, not ahead of it. Ask at a local shop before a trip, since local knowledge is current in a way no article can be.

To round out the beginner series, read our guide to how to pick your first fly rod, our guide to winter fly fishing tips and tricks, and our guide to how trout survive winter. Between the rod, the water sense, and the flies, you will have the full picture of what a trout wants and how to offer it.