RS2 Emerger Pattern: Why Trout Can't Resist This Fly

The RS2 emerger pattern is one of those flies that earns its reputation on difficult water. Developed by Rim Chung in the 1970s on Colorado’s South Platte River, the RS2 was designed specifically to fool educated tailwater trout during midge and Baetis emergences. If you’ve spent time at Cheesman Canyon or Eleven Mile, you’ve probably watched a guide clip one of these to a tippet while you wondered why such a sparse fly would possibly work.

It works because the trout tell it to work. After twenty years on Colorado tailwaters, I’ve seen the RS2 outperform flashier patterns on slow, clear runs where fish have the time to study every fiber.

What Makes the RS2 Emerger Pattern Effective

The RS2 is a study in deliberate minimalism. Rim Chung wasn’t tying a pretty fly. He was solving a specific problem: South Platte trout that had seen everything and rejected most of it. The materials he landed on, fine dubbing body, sparse Antron or CDC wing, and two tails of beaver or rabbit fiber, create a silhouette that sits right in the film or just below it, which is exactly where an emerging midge or Baetis nymph lives during a hatch.

The “RS” in the name stands for “Rim’s Semblance,” which tells you everything about the design philosophy. It’s not trying to be a photorealistic insect. It’s offering a general impression of a struggling emerger, and that impression is what triggers reflex strikes from fish that are locked into a rise form.

For anyone interested in understanding the design logic of pattern categories like this one, the Fly Tying section of this site covers the fundamentals of emerger construction in more depth.

The Emergence Window and Why It Matters

Midges and Baetis don’t just appear on the surface fully formed. There’s a transitional period where the nymph is struggling out of its shuck, suspended in or just under the film, and completely vulnerable. That’s the window the RS2 targets.

Tailwater fish, especially on regulated Colorado rivers, see so much fishing pressure that they become extraordinarily selective during this window. A size 22 RS2 in the right color will outperform a size 18 Parachute Adams during an active midge emergence because the RS2’s profile matches the actual stage of the insect the fish are eating.

Color Selection: Gray vs. Olive

Two colors dominate RS2 usage in Colorado and across the tailwater West: gray and olive. Gray matches the midge and PMD emerger profile on most South Platte drainages. Olive covers Baetis emergences and transitions into late-season blue-winged olive hatches.

The practical answer from verified buyer reports and fly shop conversations is to carry both. On a given day, the difference between gray and olive can be the difference between a fish every cast and a long, frustrating morning. If I’m fishing Cheesman and the fish are showing in shallow runs during a Baetis hatch, olive goes on first. If I’m on Eleven Mile with midges coming off, I’m reaching for gray.

Hook Size and Tippet Considerations

The RS2 shines in smaller sizes. Sizes 20 through 26 are standard operating range for tailwater midge applications. Sizes 18 and 20 work well for Baetis emergences on bigger water.

The fly’s small profile demands appropriate tippet. Most experienced tailwater anglers fish RS2 patterns on 6X, with 7X being common in technical conditions. The fine wire Mustad Signature hooks used in commercially tied versions are appropriate for these light tippet presentations because they don’t impose excessive weight that would pull the fly below its intended depth.

How to Fish the RS2 Emerger Pattern

The RS2 is a versatile fly that adapts to several presentation styles, and understanding which approach fits the conditions separates the anglers who catch fish from the ones who wonder why the pattern isn’t working.

Euro Nymphing Applications

I’ve fished euro nymphing setups on the Arkansas and South Platte since 2018, and the RS2 is a legitimate candidate for the point or dropper position when fish are actively emerging. The key is understanding that in a euro rig, the RS2 typically fishes as a near-surface dropper behind a heavier anchor fly.

Field reports from euro nymphing communities consistently describe the RS2 as an effective dropper in sizes 20 to 24, positioned 12 to 18 inches above or behind a heavier anchor nymph. The leader tension of a euro setup keeps the fly at a consistent depth, which matters during a hatch when fish are keyed to a specific zone in the water column.

Dry-Dropper and Indicator Presentations

Rigged under a small yarn or foam indicator, or dropped 12 to 18 inches below a CDC dry fly, the RS2 covers water efficiently. This is the most common presentation for anglers who aren’t euro nymphing.

The dry-dropper approach works particularly well when you’re not sure whether fish are taking on top or just below the film. A CDC Elk Hair Caddis or a small Parachute Adams up top tells you what the fish are doing on the surface while the RS2 works the film below it.

Sight Fishing to Rising Fish

On slow, clear tailwater runs where you can actually see individual fish rising, the RS2 excels as a near-dead-drift offering. Cast 3 to 4 feet above the fish’s position, mend upstream immediately, and let the fly float freely through the rise lane.

I’ll be direct about something here: this presentation sounds simple and isn’t. Reading the exact depth a fish is feeding at and placing a size 22 fly on 7X with enough slack for a drag-free drift in current seams takes practice. If you’re new to tailwater sight fishing, hire a guide for a day on the South Platte before you try to figure it out on your own. The water is technical enough that a single guided session teaches more than a season of self-taught fumbling.

Tying the RS2 Yourself

The RS2 is one of the most beginner-accessible patterns in terms of material count: two fibers for the tail, a small dubbed body, and a sparse wing of Antron or CDC. Three materials, small hooks, and a design that rewards restraint.

That said, I made exactly the classic beginner mistake years ago of buying a huge materials kit before I had consistent thread control. The RS2 on a size 22 hook will punish sloppy thread wraps. The body needs to be thin and tapered. The wing needs to be sparse. Neither of those outcomes is possible without smooth, controlled thread work.

My suggestion: spend the first several tying sessions on nothing but thread-and-hook exercises. Lay thread wraps until they’re even and consistent. Then tie the RS2. The design is forgiving in concept but unforgiving of poor fundamentals at the vise.

The real reason to tie the RS2 yourself isn’t cost savings. Tying your own flies saves money only if you tie in volume and actually fish what you tie. Most casual tyers (I was one for years) tie more than they fish and the math never works out. The genuine value is understanding. When you’ve tied 100 RS2s, you understand why the body taper and dubbing density matter to how the fly sits in the film. You understand why less Antron in the wing often produces better results than more. That understanding makes you a better angler, not just a better tyer.

If you want to go deeper on pattern design and tying technique, the fly tying resources section covers materials selection and technique progressions that apply directly to emerger patterns like this one.

Top Picks: RS2 Emerger Patterns

RS2 Gray Emerger Midge Nymph Fly

The RS2 Gray Emerger Midge Nymph Fly comes in a 12-fly pack tied on Mustad Signature hooks, with the option to select your size at checkout. Gray is the baseline RS2 color for most Colorado tailwater applications, covering midge emergences on the South Platte, the Blue River, and similar limestone-influenced systems.

Verified buyer notes indicate the flies arrive well-proportioned with appropriate Antron wing material and a smooth dubbing body. Owner reviews across multiple size options note that the Mustad Signature hook holds a consistent point and is appropriately lightweight for 6X and 7X tippet presentations. The fine wire construction is a genuine functional advantage for emerger fishing, not a marketing claim.

The 12-fly pack format makes practical sense for how the RS2 gets used. These are small flies on light tippets fished in brushy stream environments. You lose flies. Having 12 of a single color and size means you’re stocked for a serious day on the water without opening three different boxes to reassemble a working rig.

Check current price on Amazon.

RS2 Olive Emerger Midge Nymph Fly (Option A)

The RS2 Olive Emerger Midge Nymph Fly addresses Baetis and blue-winged olive emergence windows that the gray version doesn’t cover as cleanly. Olive is the go-to color when you’re fishing during Baetis activity, which in Colorado typically peaks in October through November and again in early spring.

Owner reports describe this version as consistent with the gray in construction quality, with the dubbing body color holding up reasonably well through repeated use. Field reports from anglers fishing Colorado and Wyoming tailwaters specifically call out the olive RS2 as a reliable producer during slow, selective BWO hatches. Size selection matters here: sizes 20 to 22 cover most Baetis applications, with size 24 becoming relevant on pressured spring creek environments.

The mid-range price point for a 12-fly pack positions this as a practical working box fly rather than a display piece. These are meant to get fished and replaced.

Check current price on Amazon.

RS2 Olive Emerger Midge Nymph Fly (Option B)

The RS2 Olive Emerger Midge Nymph Fly is another olive colorway option in the same 12-fly format, offering an alternative sourcing choice within the same pattern category. Verified buyers note that the hook specifications and material profile are consistent with the expected RS2 construction, making this a functional alternative if the primary olive listing shows a size you need out of stock.

From a practical standpoint, carrying two different olive RS2 sources in your box lets you compare proportions and dubbing density between tie batches. Experienced tailwater anglers often find that slight variations in body thickness or wing sparseness produce different results on different days. Having both options available gives you something to reference when one profile is working and the other isn’t.

At a mid-range price band, stocking both olive options in the sizes you fish most frequently is a reasonable approach for any angler who plans to spend serious time on technical water.

Check current price on Amazon.

Buying Guide: Choosing RS2 Emerger Patterns

Match the Color to the Hatch

Gray and olive are the two essential RS2 colors. Gray covers midge emergences, which are the dominant hatch type on Colorado tailwaters year-round. Olive covers Baetis and BWO hatches, which occur primarily in spring and fall. If you’re buying RS2 patterns for the first time, purchase both colors in size 20 and size 22 before worrying about anything else.

Local fly shop staff are a better real-time color guide than anything published online. Ark Anglers in Salida stocks what’s actually working on the Arkansas. The same principle applies to whatever shop is nearest your target water. Call ahead and ask what RS2 color and size is producing right now.

Hook Size Selection

The RS2 operating range for most tailwater applications is size 18 through 26. Beginners often buy larger sizes because the flies are easier to handle. The problem is that the fish on most pressured tailwaters are eating size 20 to 24 most of the time. Buying size 18 because it’s easier to tie on is buying a fly that doesn’t match the hatch.

For the South Platte system, size 20 and 22 cover the majority of midge and Baetis situations. Size 24 and 26 become relevant on Cheesman Canyon or Deckers during heavy fishing pressure. The fly tying approach to emerger patterns consistently emphasizes that small size imitation often outweighs perfect silhouette on selective water. Hook size is the first variable to get right.

Hook Quality and Tippet Compatibility

Fine wire hooks are functionally important on RS2 patterns, not a premium marketing feature. A heavy-wire hook on a size 22 fly will pull the pattern below the film zone it’s designed to target. Mustad Signature hooks, used in the commercially tied options covered here, represent an appropriate balance of strength and wire diameter for light-tippet emerger applications.

Match your hook size to your tippet diameter. Size 20 to 22 RS2 patterns fish well on 6X. Size 24 and smaller typically require 7X to turn over cleanly and present without spooking fish in slow, clear currents. Verified buyer reports on fine-wire RS2 patterns consistently cite fewer break-offs on 7X compared to heavier-wire alternatives.

Pack Size and Fishing Frequency

RS2 patterns in 12-fly packs represent the practical standard for working tailwater anglers. These flies get lost, broken off on fish, or destroyed by the fish themselves (a sign they’re doing the job). A single-fly purchase approach makes no sense for a pattern you’ll fish this frequently.

If you fish tailwaters two or three times per season, one pack each of gray and olive in your primary size is a reasonable starting inventory. If you’re on Colorado tailwaters regularly through the season, you’ll likely burn through a 12-pack in a season of active use. Buy accordingly.

Pre-Tied vs. Tying Your Own

Pre-tied RS2 patterns in the mid-range price band offer consistent quality for anglers who don’t tie their own flies or who want a reliable backup supply while they learn the pattern at the vise. The tying value proposition is real but misunderstood. Cost savings only materialize at volume with flies you actually fish.

The actual case for tying your own RS2 is educational. When you’ve tied 50 RS2s, you understand the body taper that lets the fly sink to the right depth. You understand the wing volume that affects how the fly sits in the film. That knowledge changes how you fish the pattern. For beginners who haven’t started tying yet, pre-tied options are the right answer while you build foundational thread skills.

Frequently Asked Questions

What size RS2 emerger should I start with?

Size 20 and size 22 cover the majority of tailwater midge and Baetis applications across the American West. These sizes are small enough to match the most common emerger profiles but large enough to handle on standard 6X tippet without excessive difficulty. If you’re fishing highly pressured water like Cheesman Canyon, size 24 should be in your box as well. Owner reports consistently identify size 22 as the single most productive RS2 size on Colorado’s South Platte system.

What is the difference between gray and olive RS2 patterns?

Gray RS2 patterns target midge emergences, which occur on tailwaters year-round. Olive RS2 patterns are designed for Baetis and blue-winged olive hatches, which peak in spring and fall across Colorado and Wyoming. Both colors fish at the same depth in the same presentations. The difference is purely about matching the insect the fish are actually eating on a given day.

Can I fish the RS2 emerger on a euro nymphing rig?

Yes, and field reports from euro nymphing communities consistently describe the RS2 as an effective near-surface dropper in a euro setup. Position it 12 to 18 inches above or behind a heavier anchor fly. The RS2 works in the RS2 in this configuration because the leader tension holds the fly at a consistent depth in the water column, which is exactly what you need during an emergence when fish are locked onto a specific feeding zone.

What tippet size should I use with RS2 emerger patterns?

Size 20 to 22 RS2 patterns fish well on 6X fluorocarbon or monofilament. Size 24 and smaller typically require 7X to turn over cleanly and present without creating drag in slow, clear current. Verified buyer notes on fine-wire RS2 patterns cite fewer tippet break-offs compared to heavier-wire alternatives at the same hook size. Match your tippet diameter to the hook size and the current speed of the water you’re fishing.

Are commercially tied RS2 patterns good enough or should I tie my own?

Commercially tied RS2 patterns in the mid-range price band are consistently reported by verified buyers as well-proportioned and fishable. For most anglers, pre-tied options are the practical answer. Tying your own is worth doing, but not primarily for cost savings. The educational value of tying the RS2 yourself, understanding why the body taper and wing sparseness affect how the fly fishes, is where the real return is.