What Is an Emerger Fly? And How Do You Fish Them?

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An emerger fly is one tied to represent the emerging stage of a mayfly, caddis, or other aquatic insects.

Using these fly patterns is a very effective way to fly fish, particularly when feeding trout are taking insects just below the surface.

In this article, we explain all about fishing emergers—what they imitate, when to use them, and how to fly fish with them effectively.

What Is an Emerger?

Emerging Graphic
During the emerger phase of an insect’s life cycle, it is vulnerable to being eaten by trout as it ascends from the bottom of the water.

The emerger phase of an insect’s life cycle begins as it ascends from the bottom of the river or lake and begins to make its way to the surface, where it will spread its wings and fly off as an adult.

Once a caddis or mayfly nymph begins its slow ascent through the water column to the surface, it is very vulnerable to being eaten by trout.

Hence the fish are very attuned to picking off emerging insects as they float upwards to the water’s surface because they are easy prey.

Often they’ll be taking these insects in the middle of the water column, but as a hatch gathers momentum, you might see them taking the emergers either on or close to the water surface.

When they are taking the emergers just under the surface, you will see that classic bulging rise (see here for a separate article on trout rise forms) where the water bulges, but you don’t see a snout poke through or break the surface (although sometimes you’ll glimpse a fin or tail as the fish turns down after feeding). This type of rise generally doesn’t generate the rise rings that a dun eat produces.

Typically when the emerging nymph reaches the top of the water, it takes some time for it to punch through the surface tension, shrug off its shuck (the shell of its exoskeleton), open its wings, and prepare to fly away.

This phase is when the emerging insects are at peak vulnerability – they are basically stuck – and the stage that we want to imitate by fishing emergers.

What Are Emerger Patterns?

Most emerger patterns are designed to imitate this phase – when the insect is trapped in the surface film.

These patterns usually have one or more elements designed to sit in or below the surface film as opposed to a dun pattern that is designed to ride high in the water.

They often have a long tail designed to represent the trailing shuck. Often they are tied on a curved hook. And they are usually sparsely dressed with less buoyant dubbing than a dun pattern.

These subtle changes are enough to differentiate emerger patterns from duns and get the eat from trout, which often become fixated on taking the emergers in preference to duns. It’s less hard work, right?

It is worth noting that for caddis flies and midge, there are flies tied to represent the pupa phase—the stage they are in as they ascend. The pupa stage with these insects is the stage between the larva (nymph) stage and the adult (dun) stage.

Pupa create a cocoon around themselves before they ascend, which caddis emerger patterns such as the LaFontaine sparkle pupa try to imitate.

Mayfly don’t have a pupa stage, so the emerging insect is a larva or nymph until it transforms into an adult dun.

How to Fly Fish an Emerger Pattern

Dry emerger flies can be fished just like a dun pattern or other dry fly. Cast them out on a leader and watch for the take.

Because emerger flies sit lower down in the surface film, they can be harder to see in low light, so it is handy to have some tied with a Hi-Vis or poly yarn post or to fish them in tandem with a more visible dun pattern. Just tie the emerger off the back of the dun or use a dry dropper rig with the dun in the top fly position. The two flies should be no more than 10 inches apart, in my view.

Of course, because aquatic insect larvae are eaten by trout as they ascend, a nymph is another option to use to target fish feeding on emergers. Often an unweighted or lightly weighted nymph pattern below a dry gets the eat, especially in the early phases of a hatch when the trout are still feeding predominantly subsurface.

Soft hackle flies are another option, as they can represent the ascending nymphs very well if fished on the swing. Soft hackles are effective during the early phase of the hatch. Remember to stay up tight to the bottom fly line or use a dry dropper rig to make sure you don’t miss the take.

Do Emerger Patterns Catch Trout?

For sure, fishing emergers is a surefire way to catch feeding trout in the right circumstances. As nymphs begin hatching and there are only a few trout rising, nymphs and soft hackles are a good option, but when the fish are up on top eating emergers, you should switch to a dry fly emerger pattern.

You should always have a good supply of emerger dry flies in your fly box. They don’t have to be elaborate patterns, but a few Klinkhammers, something like an F-Fly tied with CDC feathers, is enough to adequately represent a mayfly emerger or an emerging caddis fly.

As the hatch gathers strength, you’ll find rising fish switching to feeding on duns. While some anglers like to change to a different technique and tie on a pure dun fly pattern such as a Parachute Adams, you’ll find your emerger fly will continue to take fish.

As the fly fishing experts say, a fish taking duns will also take an emerger, but a fish locked on emergers will ignore a dun. Many times fishing emergers right through the hatch is a viable fly fishing option.

What Are Some Good Emerger Fly Patterns?

Here are some of my favorite fly patterns for fishing emergers covering mayfly, caddis, and midge.

The Klinkhammer

Klinkhammer Fly
Klinkhammer Fly

The OG of mayfly emerger patterns, the Klinkhammer is more a style of fly now than a specific pattern. There are many variants of this fly, but they all have an upright post, a parachute hackle, and a trailing tail of some sort that pokes through the surface film. Klinkhammers are always tied on a curved emerger hook.

The F-Fly

This simple fly with a thin body and CDC wing is one of the great mayfly emergers that will also be taken as a dun. Every fly fisherman should have some of this simple dry fly in their fly box

The RS2

RS emerger fly
RS Emerger Fly

This simple mayfly emerger pattern was developed in the 1970s by Colorado fly tyer Rim Chung. It is a no-hackle dry fly with a short post that comes into its own when you are fly fishing in still pools. It is tied on a straight hook and sits flush on the water in the surface tension.

LaFontaine’s Sparkle Pupa

LaFontaine Sparkle Pupa Caddis
LaFontaine Sparkle Pupa Caddis

This caddis emerger fly revolutionized fishing for caddis feeders by accurately imitating the ascending pupa. It’s vital to have these in the early stages of a caddis hatch.

The CDC Caddis Emerger

The chenille in the body of this fly absorbs water, ensuring that it rides low on the surface of the water. The deer hair provides enough floatation to keep it from sinking, and the CDC feathers in the overwing provide movement to imitate the natural. One of my favorite dry flies.

Morgan’s Para Midge

Morgan's Para Midge
Morgan’s Para Midge

With a CDC wing and Crystal Flash tail, this is one of the most effective emerger patterns for midge fishing.

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Rick Wallace is a passionate angler and fly fisher whose work has appeared in fishing publications including FlyLife. He's appeared in fishing movies, founded a successful fishing site and spends every spare moment on the water. He's into kayak fishing, ultralight lure fishing and pretty much any other kind of fishing out there.
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