Griffiths Gnat - Hi-Viz

The Griffith's Gnat — Hi-Viz

There is a fly that lives permanently at the intersection of simplicity and effectiveness — a pattern so unassuming in its construction that first-time tiers complete it in minutes, so deceptively productive in its application that guides on the most demanding tailwaters in the country reach for it when every other pattern has failed, and so elegantly designed that it has remained essentially unchanged since George Griffith tied the original version at a Trout Unlimited gathering in the early 1960s. The Griffith's Gnat is that fly. And the Hi-Viz variant — a modern update that adds a small tuft of bright indicator material to the pattern's foundation without compromising the imitative qualities that made the original legendary — extends the pattern's effectiveness into the low-light conditions, flat-water situations, and technical presentations where the original's near-invisibility on the water surface becomes a practical limitation that the angler cannot afford.

The Griffith's Gnat Hi-Viz is not a different fly from the Griffith's Gnat. It is the same fly made fishable in more situations by a single addition — a small post of white, orange, or chartreuse yarn or poly dubbing at the head that gives the angler a visual reference point without changing anything about how the fly sits in the film, how it drifts in the current, or how it presents to the fish below. That one modification transforms a fly that most anglers fish only when they can see it into a fly that produces throughout the full range of midge and cluster feeding situations — including the demanding early-morning sessions, flat-water evening rises, and low-light conditions where the original Griffith's Gnat is most desperately needed and least visible.

What Is a Griffith's Gnat

Before addressing the Hi-Viz modification specifically, understanding the original Griffith's Gnat at a foundational level is essential — because everything that makes the Hi-Viz version effective derives from the original pattern's design principles, and those principles are worth understanding in detail.

George Griffith, one of the founding members of Trout Unlimited and a dedicated Michigan fly angler, tied the original Griffith's Gnat as a midge cluster imitation — a pattern designed to represent not a single midge adult but a small group of midges clustered together on the water's surface, as commonly occurs during dense midge hatches when adults accumulate in the surface film in numbers high enough that individual insects merge into clusters visible to feeding trout as a single larger food item. The fly's construction — a body of peacock herl palmered with grizzly hackle — achieves this cluster suggestion through the interaction of the two materials rather than through any explicit structural imitation of multiple insects.

Peacock herl, with its natural iridescence and light-shifting quality that makes it effective across so many proven patterns, creates a body that catches light differently at every angle — appearing dark olive in one light, bright green in another, almost black in a third. This shifting quality suggests the random, organic collection of multiple midge bodies seen from below in a way that a single, uniformly colored body does not. The palmered grizzly hackle wrapped through the peacock body creates a radial, three-dimensional profile that suggests the overlapping wings of clustered midge adults simultaneously with the natural shimmer of the herl — an interaction of two materials that produces an imitative quality neither could achieve alone.

The result is a fly that works as a single midge adult in small sizes on selective fish, as a midge cluster imitation in larger sizes during dense hatches, and as a general impression of surface film activity that trout associate with food across a broader range of situations than either a precise single midge or a structured cluster imitation produces. That versatility across multiple imitative applications in a single pattern is what elevated the Griffith's Gnat from clever regional fly to one of the most important patterns in the modern fly fishing vocabulary.

The Problem the Hi-Viz Solves

The original Griffith's Gnat has one practical limitation that no amount of angling skill or tying refinement can overcome — it is nearly invisible on the water's surface at any casting distance beyond fifteen feet in most light conditions. A size 22 Griffith's Gnat tied on a fine-wire hook with peacock herl and dark grizzly hackle sits low in the film, dark in color, and approximately the size of a sesame seed. In the flat, glassy water where midge fishing is most productive — the calm pools and slow glides of tailwaters and spring creeks — the fly disappears entirely against the reflective surface at the distances required to present to educated fish without disturbing them.

This visibility problem is not trivial. An angler who cannot see the fly cannot track its position through the drift, cannot identify when it reaches a rising fish's feeding lane, and cannot detect the subtle take of a large tailwater trout that has intercepted the fly so gently that the tippet barely moved. The consequence is missed takes — takes that happen during the drift but that the angler does not detect until the fish has already rejected the fly and returned to feeding on naturals. On a good Trico or midge morning where fish are rising every five seconds and takes are frequent, missing half of them because the fly is invisible at twelve feet costs the angler the most productive part of the session.

The Hi-Viz post solves this problem at the cost of adding one small piece of bright material to the head of the fly — a cost so minimal in imitative terms that it is essentially zero. The post does not change the fly's posture in the water. It does not alter the peacock herl body's light-shifting quality. It does not affect the grizzly hackle's presentation in the film. It sits above the fly rather than in or on it, visible to the angler above the water without being visible to the fish below the surface in the same way that a parachute post on a Parachute Adams provides angler visibility without compromising the fly's underwater presentation. A fish looking up at a Hi-Viz Griffith's Gnat from below sees the same fly as it sees looking up at the standard version — a cluster of midges in the surface film — because the post extends upward into the air rather than into the fish's field of view.

Midge Biology — The Griffith's Gnat's Foundation

The Griffith's Gnat Hi-Viz's effectiveness begins with the biology of midges — specifically the Chironomidae family that constitutes the most numerous aquatic insect in most cold water trout fisheries and the food source that tailwater and spring creek trout eat more consistently and more continuously than any other insect across all twelve months of the year.

Midge adults emerge through the surface film and gather on the water's surface in numbers that, during dense hatches, can exceed any other insect emergence in terms of sheer density of insects per square foot of river surface. On tailwaters like the San Juan, the South Platte, and the Bighorn, midge hatches occur every day of the year regardless of air temperature, water temperature, or weather conditions — a biological reality that makes midge imitations not optional equipment for tailwater fishing but mandatory components of any serious angler's box regardless of season.

The clustering behavior that the Griffith's Gnat specifically imitates occurs when emerging midge adults gather on the water's surface after shedding their pupal shucks — standing or skating briefly on the surface as their wings dry before taking flight. During dense hatches this gathering produces visible clusters of adults that accumulate in calm surface water, current edges, and the surface eddies behind rocks and current obstructions. These clusters are specifically targeted by trout that have learned — through years of feeding experience on dense tailwater midge hatches — that intercepting a cluster of four to six adults in a single rise is significantly more calorie-efficient than rising individually to each adult.

The angler who observes midge feeding trout carefully during a dense hatch and notes that some fish are rising to the open surface in fast, frequent rises — individual adult feeding — while others are making slower, more deliberate rises in the calm water and current edges — cluster feeding — is making a distinction that directly affects fly selection. The fast, frequent individual feeder may respond to a size 24 single midge adult pattern. The slower, deliberate cluster feeder is looking specifically for the size 16 to 20 cluster that the Griffith's Gnat Hi-Viz represents.

When and Where the Griffith's Gnat Hi-Viz Performs

The Griffith's Gnat Hi-Viz is a year-round pattern on tailwaters and spring creeks and a late-spring-through-fall pattern on freestone rivers — a productive window that makes it relevant across more calendar days than most dry fly patterns and that rewards anglers who understand its seasonal applications specifically.

Winter tailwater midge fishing is the Griffith's Gnat Hi-Viz's most exclusive application — the period when most dry flies are stored for the season but when midge hatches on rivers like the San Juan and South Platte continue producing surface feeding fish that reward anglers willing to fish in cold temperatures with tiny flies on fine tippet. Winter midge emergences on productive tailwaters can be spectacular in density — warm midday temperatures on clear winter days trigger emergence events that cover the surface with adults and produce rising fish from banks that appear completely dead in the morning cold. A size 18 or 20 Griffith's Gnat Hi-Viz during a winter midge hatch is one of the most productive and least pressured dry fly situations available to the patient, cold-tolerant angler.

Spring brings the Griffith's Gnat Hi-Viz into relevance on freestone rivers as the first significant midge hatches of the year begin before most other insects are active. On western freestone rivers from late March through May, before the salmonfly and caddis hatches that define the spring fishing season begin, midge activity provides the earliest consistent dry fly opportunities of the year — opportunities that the Griffith's Gnat Hi-Viz covers as effectively as any pattern available.

Summer is the season of the Griffith's Gnat Hi-Viz as a between-hatch pattern on tailwaters and spring creeks — a fly that fills the difficult midday window when major hatches have passed and fish have returned to their holding lies feeding opportunistically on the background midge activity that continues throughout the day on most productive tailwaters. When fish are visible in the surface feeding film but not responding to any specific hatch pattern, the Griffith's Gnat Hi-Viz in size 18 through 22 produces takes that larger, more specific patterns do not during this demanding window.

The evening midge hatch on tailwaters is another signature Griffith's Gnat Hi-Viz application. As temperatures cool and late afternoon transitions to evening on most tailwaters, midge activity increases and the surface feeding that accompanies it often produces the most consistent and most productive dry fly fishing of the day. The low light conditions of the evening hatch — the specific conditions under which the Hi-Viz post provides its most significant practical advantage over the original — make the Hi-Viz variant the more productive version during this window simply because the angler can see it and track it through the complex surface conditions of the evening rise.

Fall is perhaps the most overlooked season for Griffith's Gnat Hi-Viz fishing on freestone rivers. As water temperatures drop and the major hatches of summer give way to the Blue Winged Olive and midge activity that defines the autumn fishery, midge cluster fishing on the flat, slow sections of western rivers produces extraordinary fish — large, pre-spawn brown trout that are feeding heavily across all food sources and that respond to a well-presented Griffith's Gnat Hi-Viz cluster pattern with takes that the season's other hatches do not regularly produce.

How to Fish the Griffith's Gnat Hi-Viz

The Griffith's Gnat Hi-Viz rewards the same general approach as all midge and small dry fly fishing — fine tippet, precise presentation, drag-free drift, and careful positioning — but with several specific techniques that maximize its effectiveness across the range of situations it covers.

Dead drift is the primary and most consistently effective presentation across all Griffith's Gnat Hi-Viz applications. The fly's effectiveness does not depend on movement — the peacock herl body and palmered hackle create sufficient visual interest and imitative accuracy at rest to produce takes from feeding fish without any animation from the angler. Allowing the fly to drift completely naturally through feeding lanes, with no tension in the tippet that creates even subtle drag, is the non-negotiable foundation of consistent success with this pattern.

The surface film presentation requires specific attention to floatant application. Over-treatment with floatant causes the Griffith's Gnat to ride too high on the hackle tips rather than sitting flush in the film — a posture that is less imitative of both single midge adults and midge clusters, which sit with their bodies in rather than above the surface tension. Apply floatant sparingly to the hackle only and allow the peacock body to contact the surface film without waterproofing treatment that keeps it elevated above the water. If the fly rides too high after initial treatment, a single touch of the hook to the water's surface before the cast — wetting the body slightly — settles it into the correct film-riding position.

The twitched presentation is worth employing during active midge emergences when adults are skating and gathering on the surface — a brief, gentle twitch that moves the fly two to three inches across the surface can trigger strikes from fish that have been following a dead-drifted fly without committing by replicating the skating behavior of a natural adult in the process of taking flight. This is a subtle twitch — far gentler than the sharp hop of a hopper presentation — that barely disturbs the surface before the fly settles back to a dead drift.

The dry-dry rig with the Griffith's Gnat Hi-Viz as the trailer below a larger, more visible dry fly — a Parachute Adams, an Elk Hair Caddis, or any other size 14 or 16 attractor — provides the angler with a clear sighting reference while the Griffith's Gnat Hi-Viz does the productive work in the film below. This rig is particularly effective during complex multi-species surface feeding situations when both larger food items and midge clusters are available simultaneously — the larger fly covers fish feeding on the more substantial surface insects while the trailing Griffith's Gnat covers fish feeding on clusters, and the two presentations operate simultaneously without requiring the angler to choose between them.

Fishing the Griffith's Gnat Hi-Viz as a dropper below a standard dry fly during hatch periods is a technique that most anglers associate with nymph droppers rather than surface fly droppers, but the combination of a visible dry fly above and a midge cluster pattern below — both on the surface — covers the full range of surface feeding behavior during complex midge emergences in a single efficient rig.

Leader and Tippet Configuration

Fine tippet is essential for effective Griffith's Gnat Hi-Viz fishing across most of its applications — the same tippet considerations that govern all midge dry fly fishing apply to this pattern with equal force.

Five-X tippet is the maximum appropriate diameter for any Griffith's Gnat Hi-Viz application except the largest sizes in fast water where tippet visibility is not a meaningful concern. On most tailwaters and spring creeks where the pattern is most productive, 6X is the standard and 7X is frequently required for the most selective fish in the flattest, clearest water. The relationship between tippet diameter and refusal rate on tailwater and spring creek midge feeders is direct and measurable — heavier tippet produces more refusals than lighter tippet from the same fish presented with the same fly and presentation, and the investment in developing the knot tying skill to fish 7X reliably pays dividends in fish caught throughout the season.

Fluorocarbon tippet provides a genuine advantage in Griffith's Gnat Hi-Viz applications for the same reasons it benefits all midge fishing — the reduced refractive index that makes it less visible in water than nylon monofilament, the increased abrasion resistance on rocky tailwater substrate, and the slight additional density that helps the tippet sink below the surface film rather than lying on it where it creates visible drag lines on flat water surfaces. The difference between fluorocarbon and nylon tippet in midge fishing is not always decisive but is consistently meaningful on the most demanding tailwater and spring creek water.

Leader length should be extended beyond the standard 9-foot configuration for most Griffith's Gnat Hi-Viz fishing. A 12-foot leader with an extended fine tippet section of 24 to 36 inches provides the additional delicacy of presentation and tippet flexibility at the fly that flat-water midge fishing requires, reducing drag in complex currents and allowing the fly to drift more naturally through the varying micro-currents of productive midge feeding lanes.

The Hi-Viz Post — Color Selection

The indicator post on the Griffith's Gnat Hi-Viz is available in several colors, and while the choice of post color is primarily a practical decision about visibility rather than an imitative one, understanding which colors work best in which light conditions improves the pattern's practical effectiveness.

White is the most universally visible post color across the widest range of light conditions and water types. In bright overhead light on summer mornings, white provides excellent contrast against both the dark river surface and the light sky background that the angler views the fly against depending on position. In the overcast conditions that frequently accompany the most productive midge fishing, white maintains visibility where brighter colors can paradoxically appear washed out.

Orange is the most effective post color in early morning and late evening low-light conditions — the specific times when midge fishing is most productive and the Hi-Viz modification provides its greatest practical advantage. The warm, red-orange tone that appears most visible in the slanted light of morning and evening makes orange the single most practical post color for anglers who fish primarily during these hours.

Chartreuse provides maximum contrast in any light condition and is the right choice for anglers with color vision characteristics that make white or orange difficult to see at small sizes. Its extreme brightness cuts through glare and surface complexity more effectively than natural colors and provides reliable visibility even at the distances that flat-water midge fishing requires.

Yellow represents a compromise between the extreme brightness of chartreuse and the natural appearance of white, providing good visibility across most conditions without the visual intensity of chartreuse that some anglers find difficult to use as a precise sighting reference.

Carry the Griffith's Gnat Hi-Viz in at least two post colors — white for general use and orange or chartreuse for low-light applications — and switch between them as light conditions change through the fishing session.

Size Selection

Size selection with the Griffith's Gnat Hi-Viz follows the same logic as all midge pattern sizing — matching the size of the naturals present is the foundational decision, with the additional consideration that the cluster-imitation function of the pattern means the appropriate size for cluster feeding fish may be larger than the individual midge size on the water.

Size 14 and 16 are the cluster sizes — appropriate for dense midge emergences where fish are feeding on accumulated groups of adults rather than individual insects, for the slow-water eddy positions where clusters concentrate, and for early-season midge hatches when adult midges on some rivers run larger than the tiny midge species of midsummer.

Size 18 is the most broadly useful size in a complete Griffith's Gnat Hi-Viz selection, covering both small cluster situations and single adult imitation on most tailwaters where the dominant midge species fall in the medium size range. If a single size must be chosen for the widest range of Griffith's Gnat Hi-Viz applications, size 18 is the right choice.

Size 20 and 22 are the technical single adult sizes for the most demanding tailwater and spring creek applications — the sizes required when fish are feeding selectively on individual adult midges in clear, flat water where exact size matching is the determining variable between consistent takes and consistent refusals.

Size 24 and 26 are for the smallest midge species on the most demanding tailwaters — the South Platte above Cheesman Canyon, the technical sections of the San Juan, and the limestone spring creeks where truly tiny midge species dominate the surface film during the densest hatches. At these sizes the Hi-Viz post is not merely useful but essential, because a size 26 Griffith's Gnat without any indicator feature is invisible to the angler at any practical casting distance.

Target Species

Brown trout are the Griffith's Gnat Hi-Viz's most demanding and most rewarding target — the large, educated brown trout of pressured tailwaters and spring creeks that have learned to feed selectively on the smallest and most abundant food items their rivers produce represent the specific challenge for which the combination of the Griffith's Gnat's proven cluster imitation and the Hi-Viz post's visibility advantage was developed. A size 22 Griffith's Gnat Hi-Viz presented on 7X fluorocarbon to a large brown trout feeding on a winter midge hatch on the South Platte is one of the most technically sophisticated and most satisfying dry fly situations in North American angling.

Rainbow trout on tailwaters with dense midge populations — the San Juan, the Bighorn, the Missouri — feed on midge clusters and single adults throughout the season with a consistency that makes the Griffith's Gnat Hi-Viz an essential component of any tailwater dry fly box. The San Juan River's extraordinary midge fishing — arguably the most consistent surface midge action on any river in the country — is most effectively fished with cluster patterns in the size 16 to 20 range during the peak midday emergences that define the San Juan's dry fly experience.

Cutthroat trout on spring creeks and the flat sections of western freestone rivers with significant midge populations eat Griffith's Gnat Hi-Viz patterns throughout the summer season with a willingness that makes them accessible and satisfying midge dry fly targets for anglers developing the fine-tippet and small-fly skills that this fishing demands.

Brook trout in spring-fed streams and cold-water ponds where midge populations are dense respond to Griffith's Gnat Hi-Viz presentations with the eager take that characterizes brook trout surface feeding — their tendency to rise confidently to midge cluster imitations makes them enjoyable targets for anglers practicing the technical skills that Griffith's Gnat fishing requires.

Golden trout in high alpine lakes where midge and mosquito populations are the dominant surface food source eat Griffith's Gnat Hi-Viz patterns consistently throughout the summer season — the Hi-Viz post's visibility in the bright, direct light of high-elevation environments makes it particularly practical for backcountry anglers stalking visible fish in clear, shallow water where a standard dark midge pattern would be impossible to track.

George Griffith's Lasting Contribution

George Griffith tied the original Griffith's Gnat as a practical solution to a specific fishing problem — the need for a simple, effective midge cluster imitation that could be tied quickly and fished confidently on the rivers of Michigan where the pattern was developed. He could not have anticipated that a fly tied with two materials on a small hook at a Trout Unlimited meeting would become one of the most widely carried and most consistently productive small dry flies in the modern fly fishing vocabulary — a pattern that guides on the San Juan, the South Platte, and the Henry's Fork consider as important as any other fly in their boxes and that serious anglers across North America carry as a matter of course throughout the season.

The Hi-Viz modification extends Griffith's original contribution into the practical realities of modern fly fishing — the reality that most of the fishing situations where the Griffith's Gnat is most needed are also the situations where its original nearly invisible configuration is most limiting. By adding a small tuft of bright material to a pattern that already works, the Hi-Viz variant makes one of fly fishing's most important small flies fishable across the full range of conditions it was designed to address — including the low light, flat water, and technical presentations where seeing the fly is as important as having the right fly.

Carry it in sizes 16 through 26. Carry it in multiple post colors. Fish it whenever fish are rising and the hatch is too small, too dense, or too complex for a specific single-insect imitation to provide a reliable answer. And trust it — because the peacock herl and grizzly hackle that George Griffith combined six decades ago have been providing reliable answers on the most demanding midge water in North America ever since.

Pair it with: A size 14 or 16 Parachute Adams or Elk Hair Caddis as the sighting fly in a dry-dry rig above the Griffith's Gnat Hi-Viz for a two-surface-fly presentation that covers both larger food items and midge clusters simultaneously during complex multi-species emergences. During winter and early spring tailwater midge sessions, pair the Griffith's Gnat Hi-Viz with a size 20 or 22 Zebra Midge or RS2 on a 14-inch dropper below for a surface and sub-surface two-fly rig that covers fish feeding at both the surface and in the mid-column during extended midge emergence events.

Best rivers: San Juan River, South Platte River, Frying Pan River, Bighorn River, Missouri River, Henry's Fork, Madison River, Delaware River, Armstrong Spring Creek, Nelson's Spring Creek, DePuy's Spring Creek, Farmington River, Gallatin River, Green River, Provo River, Au Sable River, Housatonic River