Adding Triggers to Fly Patterns: Subliminal Messaging for Trout

Updated: Jun 8

If you look at the majority of fly patterns fished throughout the western United States, you have to admit they are mostly designed for specific tasks. We've embraced the challenge of trying to develop flies that look exceedingly realistic to specific stream-side insects. The armada of PMD imitations are all focused on looking like PMDs and not much else. Most caddis patterns are meant for caddis hatches, etc...

Now compare this approach to the Euro-nymphing world where precise imitations aren't the preferred approach to fly-tying. Euro nymphs embrace nondescript, albeit sometimes flashy, generalizations. The focus is squarely set on the weight of your flies and their presentation; a stark contrast to what I see as the accepted western method of identifying and mimicking insects that are active in the water system that you're fishing. Obviously, this is not always true; we do fish attractors out west, but generally, the focus is on matching the hatches. But is hatch-matching more productive than flashy attractors? Well, you don't see the competition guys trying to excessively match hatches — they carry a broad swath of flies for all situations.

I'm sure by now you've seen plenty of jigged Euro-nymphs across Instagram or in fly shops. Like me, you've also probably thought, "How the hell do these catch fish?!" But, is it possible we western US anglers are so steeped in "match the hatch" lore, that we've forgotten how to broadly instigate trout takes?

You might be reading this and thinking that I'm nuts, but think about this:

You're on the stream bank and notice caddis flies bouncing on the water's surface and in the stream-side vegetation. So you grab an Elk Hair Caddis to match the hatch. You catch fish, possibly quite a few, which reinforcing your belief that the Elk Hair Caddis works well during a caddis hatch. DUH! Then, next time you're fishing and there are no caddis flying about, you might not reach for the Elk Hair Caddis. But, can you honestly tell me that the Elk Hair Caddis is a realistic caddis impersonation? Seen from below, I'd argue that an Elk Hair could be used for many different situations. Interestingly, the Adams was originally tied as a caddis imitation. I bet you mainly fish it for mayflies now though... But we are so ingrained in assigning certain patterns specific roles that we forget about the general "buggy-ness" that entices trout in the first place.

This scenario explains how we've become overrun with fly patterns to consider. Too many different patterns have been developed and broadcast for specific imitations of specific insects, even for specific rivers. On any fishing report, you'll see a dozen recommended patterns and only know half of them by name. Then compare those recommended flies to another site, my guess is that you'll see a dozen completely differently named patterns for the same stretch of water. Yet, if both reports are up to date, which set of flies work best?

I concede that I love having variety in my fly box. But fish, even when selective, have specific visual cues they use when scanning for drifting food. At times these cues can be very specific, other times they are more generalized. The most important cues might change at times from the size, color, or silhouette of a fly, but that's how trout make feeding decisions. We might carry a lot of patterns, but if none match the searching terms outlined by trout, then what are they good for? I'm also guilty of thinking that flies that previously worked for a very specific instance will fish as well in future outings. I believe this type of thinking has lead to the deployment of many fly patterns that were appropriate for certain circumstances, but very rarely broadly applicable. Plus, are we confident we know exactly when the conditions are just right for employing that secret pattern?

These issues almost rarely come up when presenting attractor flies, Euro-nymphs etc... Simply visit a website with fly patterns from the U.K. and you'll notice flies are much different. There are fewer, and many are pretty basic (by some tiers standards). I don't mean to say they are rudimentary, but they aren't overdressed with excessive materials. I don't mean to say US patterns are bad either, but all good flies have something in common. They focus on three keys concepts, which involve a sort of subliminal messaging to trout that "THIS is the bug you want. All the cool trout are eating it, you don't want to miss out!"


Key #1: Supernormal Stimuli (Hijacking Evolution)

You had to know the biology references were coming folks. Don't glaze over, this is where things get good. What are supernormal stimuli (SNS) and how does it apply to trout fishing?

A SNS is an exaggerated version of a stimulus that elicits a stronger response than the common version of the same stimulus. There are many examples throughout nature, from fish, to birds, even humans. An easy example is the taste of junk food, where our natural rewards system is hijacked as we indulge in these treats, especially compared to more natural, whole foods. Other examples include male fish showing increasingly aggressive responses to overly-red prosthetic fish (spawning colors of males), which are typically much redder than naturally occurring red on other males. So how does this relate to fly tying and catching trout? By exaggerating certain properties of our flies or motion of a fly, we can hijack the process of how trout develop cues to identify food. There are certain qualities that distinguish trout food from the other detritus that floats by, and exaggerating these qualities can convince a fish that it's "go time!" This is especially true with predatory trout whereby an angler presents a stimuli that elicits a vicious strike response even when the trout isn't actively feeding. This is a major concept in the Kelly Galloup school of streamer presentation.

Let's consider some examples:

The Prince Nymph: Exaggerated long white biots give the illusion of wing buds but leaves the subtlety at home, as they are much more prominent than buds you'd see on typical trout food. Or do they look like legs? Soft hackle gives the illusion of moving legs but doesn't limit the look to a few feathers on either side. In my opinion, both the biots and soft hackle are strong examples of SNS.

Pat's Rubber Legs: Without the legs what is it? A twig floating by? With the extra-long, wiggly legs, this fly is all movement, which mimics a living vertebrate. In case you didn't already know, movement is key for predators.

Pheasant Tail Nymph: Slim profile similar to mayflies, but the iridescence of peacock hurl on the thorax, coupled with the legs, highlights the distinct silhouette that makes this fly so famous.

If I were to generalize, the most important features are (in no specific order) size, shape, movement, and color/contrast.

Key #2: Hotspots

Now, about those gaudy attractors and Euronymphs. Why include ice-dub hotspots, shiny beads, and fluorescent collars? You know what floats down the river and doesn't have hotspots, beads, or fluorescent reds, oranges, greens, blues or purples? The stuff trout don't eat. Pebbles, leaf chunks, twigs. Most is all drab, most is non-nutritious. What can be flashy in rivers? In some insects, especially midges, exoskeletons inflate with air to aid in emergence, which provides an unmistakable sheen on emergers. So, flash can actually prove to be highly imitative, not limited to only attraction. Either way, the combo 1-2 punch of SNS and "hotspotting" fly patterns, can quickly grab a fish's attention, then provide the needed stimuli to convince him that it's feeding time. Contrasting colors is common in these flies, as well.

Let's consider some examples:

Egan's Red Dart: Pretty much a prince nymph with exaggerated colors that really shift the conversation from "That's not food!" to "What is that?!, I'm suddenly very curious."

Walt's Worm: A bland dubbed body is not much to write home about, but add a hotspot collar and that chuck is transformed into any number of food items. Simply getting the fish's attention is half the battle. No fish is going to eat your fly if they don't notice it.

Red Tag: Wet or dry, the fly is very classic. Add a red tag and the fish notice the pattern against an otherwise drab surrounding. Once noticed, the trout is reminded of the food items that the Red Tag could be impersonating; the Red Tag could be anything. That leads us to Key #3.

Key #3: Food Inception

You have to plant the idea that the fly is food into the fish's brain. I give Bob Wyatt credit for this and I don't know of any science behind it, but believe this concept holds water. Here's how: by presenting a general pattern without overt detail, the fish has to actively think about and decode the pattern and convince itself that it's edible. Conversely, the more detail you throw into a pattern, the greater the opportunity for mismatching the trout’s exact visual cue of what constitutes food.

Without detail, trout can fill in the blanks and convince themselves to take a nibble, while added detail may give a fish reason to be skeptical and pass on your fly. It's all very reminiscent of the quote, "Better to remain silent and thought a fool than to speak and remove all doubt."

Let's consider a good example: Gold Ribbed Hare's Ear. In its simplest form, it's so generically nondescript that it could really be anything. Is it a mayfly, or stonefly, or caddis pupae, or scud, or fry, or baitfish, or damsel nymphs, or something else? YEP!

Now a bad example: No discredit to the amazing tying ability needed to create an ultra-realistic pattern, but often they function more as a static piece of art than a working fly. They can look as real as they want, but in reality, they will always have a hook hanging off which will never look like the real deal. That's why we utilize the above keys to override any fish hesitation.


I refrained from compiling a full list of every trigger point that might exist, as I think there could be many that we don't fully understand. And given enough time and ingenuity, we will continue to develop even more in the future. Nonetheless, every good pattern should have some kind of trigger point that plays on (at least one of) the three key concepts I've outlined here. Finally, you can dress up your patterns all you want, but if you're missing a key component, then you've tied window dressing. (Sometimes window dressings sell really well). So, keep these keys in mind when assessing fly patterns in fly shops or when at your own vise.

Interested in more: Read our post "The Mind of A Picky Trout".


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  1. Wyatt, B. 2013. What Trout Want: The Educated Trout and Other Myths.

  2. Fly Fishing Devon. Ethological Experiments.

  3. Grubb. T.C. 2003. The Mind of The Trout.


  5. Tightline Productions. Youtube.

  6. FrostFly Productions. Youtube.