How to Pick The Right Fly (Without Any Bug Knowledge!)

12 mins read
By Spencer Durrant

What question has every angler asked for as long as mankind has gone fishing?

What are the fish eating?

Answer this question correctly and you’ll put fish in the net. Get it wrong, and you’ll spend more time staring frustrated at your fly box than you will fishing.

So, how do you answer this question correctly? Especially if you’ve just started fly fishing?

It all boils down to observation. Pay attention to your surroundings – what the water and fish are telling you – and you’ll have all the information you need to make an informed, educated decision on which fly to use, even if you don’t know the first thing about aquatic insects.

Of course, the end goal is learning to identify major aquatic insects immediately, but that takes time. You can stare at pictures of blue-winged olives online all day, but identifying one out on the water permanently cements that lesson.

In this post, we’ll focus on a few of the observational skills you need to make an educated fly choice, even if you’re still learning the difference between a caddis, mayfly, and stonefly.

Observational Skills

To make the right fly choice – even without intimate knowledge of aquatic insects – you need to observe three things:

  • What’s on the water
  • What’s in the water
  • What’s near the water

Let’s dive into each of these in more detail.

close up shot of a brown trout rising to eat a mayfly off the river's surface

What’s on the water?

When you first pull up to the river, leave your fly rod in the case and just spend a few minutes observing the river’s surface. You’ll learn a ton from just five minutes of observing the water.

What bugs are on the water’s surface? What’s buzzing in the air? Are fish eating off the river’s surface? If bugs and fish are active on the water’s surface, then your fly choice is a no-brainer – you need a dry fly. If not, let’s see whats happening underwater.

What’s in the water?

Even if you see some bugs on the water’s surface, it’s always a good idea to check out what bugs are swimming beneath. The vast majority of a trout’s diet is nymphs, so fishing a nymph is almost always a good bet.

Turn over some rocks and pay attention to the bugs you see. Simply observing what bugs are crawling around beneath the water’s surface can help you make an educated fly choice. Take note of what you see, too – are the bugs small, or big? Do they have segmented bodies, tons of legs, and large tails? These details are key to picking the right fly.

What’s near the water?

Lastly, pay attention to any bugs you see and hear in the grass or trees near the river. Cicadas make an awful racket, and grasshoppers can, too. Watch and listen to see if there are any terrestrial (land-based) insects that fish might be snacking on. Wind can knock these bugs into the water, and they’re an insanely high-protein food source for fish that are always on the hunt for their next meal. Trout chase terrestrial insects with the kind of reckless abandon of kids running after an ice cream truck.

As you observe what’s on, in, or near the water, you’ll gather plenty of clues to help you make a good fly choice. So, let’s go through how you use all this information to pick the right fly.

Now you match the hatch

You’ve probably heard the phrase “match the hatch” before. In simplest terms, it refers to the practice of matching your fly choice to what bugs are actively hatching (often, “match the hatch” is used when discussing dry fly fishing).

Now that you’ve observed what bugs are on, in, or near the water, you have the information you need to pick the right fly from your box. But how exactly should you choose? Does color matter more, or does the shape of the fly?

Those are great questions. Let’s answer them.

Size matters

Some bugs are inherently bigger than others. Scuds – a popular nymph – are usually a lot bigger than midge nymphs. Stoneflies are often larger than mayflies, in both nymph and dry fly forms. So, the first step to picking the right fly is to settle on a pattern that’s close in size to what you’ve observed on, in, or near the water.

If you see fish actively rising and eating bugs on the surface, you should turn to your dry flies. If there’s not much surface action happening but you find plenty of bugs under some rocks, start sorting through your nymphs. At this stage, only look for flies that are similar in size to the real bugs you just observed.

This is why you need a good variety of size among the fly patterns in your box. I like to carry nymphs and dry flies in sizes 12 – 18, because those tend to cover most of my fishing situations. The more you fish, the more you’ll get a feel for the variety of size you need for your specific waters.

Shape is next

After size, shape is the next most important factor to base your fly choice on.

Take a long look at the fly you’re trying to imitate. For the sake of argument, let’s say you found a bunch of bugs under a submerged rock, so you decide to tie on a nymph. The insects look like they’re about a size 16. They look something like this:

This bug has a slender, segmented body, no real legs, and no real tail. Based on those characteristics, you decide that the zebra midge in your box most closely matches this bug. A zebra midge looks like this:

While the zebra midge fly doesn’t look exactly like the bug you found under a rock, it’s a pretty close match. That’s what you’re trying to do here – make a match to your flies that’s as close as possible to what you found in the water. Most flies don’t look exactly like a real insect, either, so don’t expect an exact match.

If you decided to match a dry fly, you might have found a bug that looks like this, floating down the river’s surface:

Let’s say this fly looks like it’s about a size 14, so you look through your dry flies to find some that match that size. Then, you start looking at this bug’s characteristics. It has long, slender tails, a segmented body, and big wings.

Again you’re not looking for an exact match in your box. Get as close as you can. In this instance, a Parachute Adams (see picture below) is a good match for the bug you found floating on the water.

Match color if you can

The least important factor to match is color. Trout care far more about the size and shape of your flies than they do the color. If you have a fly in your box that’s a perfect size, shape, and color match – awesome! If it matches size and shape, but it’s the wrong color, don’t be afraid to use it. The fish will usually ignore the color, so long as you get the size and shape correct.

Color becomes more important if you’re fishing heavily pressured tailwaters. Fish that see a ton of flies from hundreds of anglers grow more discerning, and key in on certain colors. So, while color doesn’t matter as much in a high mountain stream, it can impact your success on tailwaters. This shows why it’s so important to have such a wide variety of flies in your box. The more flies you have, the better chance you have to find a match, and start putting fish in the net.

You need these flies in your box

You don’t need an exact scientific knowledge of aquatic insects to match the hatch. It’s entirely possible to be a successful angler just by observing what the fish are eating, and doing your best to imitate that food source. Picking the right fly depends far more on your observational skills than it does your ability to differentiate tricos from midges.

We’ve discussed how important it is to have a big variety of flies in your box. The only problem is that there are thousands of flies out there, so knowing where to start gets tough.

That’s why we’ve put together our Fly Collections. We built them to include all the major fly types, in all the sizes, shapes, and colors needed to catch some fish. We’ve done our best to eliminate the guesswork and provide a strong foundation to match the hatch, no matter where you’re fishing. Check them out here.

Now, this isn’t the last post about choosing flies. This is part 1 in a series of articles about each specific bug type, to help you quickly and easily identify what bugs the fish are eating. In part 2, we’ll be covering the most iconic bug type in fly fishing—the Mayfly!


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