Tying the Trico Spinner: The Smallest Fly That Creates the Biggest Challenge

Tying the Trico Spinner: The Smallest Fly That Creates the Biggest Challenge

The Trico spinner fall is the most technical dry fly fishing on earth. It is also, for a certain kind of angler, the most addictive.

Here is the scenario: it's 8:30 on an August morning. The air temperature has just crossed 68°F. Above the riffle, a cloud of tiny white-winged mayflies, each one barely bigger than a grain of rice, is mating, dying, and falling to the water in numbers that defy comprehension. Thousands of spent spinners blanket every square foot of the surface, wings outstretched, bodies spent. And every trout in the river is rising.

The rises are subtle, tiny sips, barely audible, the kind of rise form you'd miss if you weren't looking for it. The trout are feeding with metronomic efficiency, sliding left and right in their lanes, inhaling spinner after spinner with the mechanical precision of a machine. Vince Marinaro, the godfather of American technical dry fly fishing, once watched a single brown trout on Pennsylvania's Letort Spring Run eat 67 natural Trico spinners in one minute. Your job is to present one artificial fly, tied on a #22 hook, riding flush in the surface film, dragging not at all, and convince that fish to eat yours instead of the sixty-seven real ones drifting past its nose every sixty seconds.

Marinaro called the Trico the "White-Winged Curse." He was being generous.

The Insect

Tricos (Tricorythodes) are among the smallest mayflies in North America, with bodies measuring 3-6 millimeters, roughly the size of a comma on this page. They inhabit spring creeks, tailwaters, and slow-moving rivers with stable flows and consistent temperatures, where their nymphs live among moss and vegetation on the streambed.

The life cycle unfolds on a precise schedule. Male duns emerge during the night or pre-dawn hours. Female duns hatch in the early morning, typically between 7 and 9 AM. Unlike most mayflies, Tricos molt from dun to spinner extraordinarily fast, sometimes within minutes. By mid-morning, males have swarmed above the riffles, females have flown into the swarm to mate, and both sexes have fallen to the water as spent spinners. The wings lie flat on the surface, hyaline, nearly transparent, catching the light like tiny panes of glass.

Males are black or chocolate-bodied. Females have olive abdomens that turn creamy white after they've dropped their eggs. This male-female color difference matters at the vise, you need both colors in your box, and which one the fish are eating depends on timing and how far into the spinner fall you are.

The spinner fall typically begins when air temperature reaches approximately 68°F. Early in the season (July), this might not happen until 9 or 10 AM. By September, it starts earlier as mornings cool. The entire event lasts one to three hours, and then it's over, the water clears, the rises stop, and the river looks like nothing happened. Until tomorrow morning, when it happens again.

The History

Tricos entered the fly fishing consciousness through a 1969 Outdoor Life article by Vince Marinaro, who initially misidentified them as Caenis (another tiny mayfly genus). His fishing partner Charlie Fox encouraged anglers to tie size 22 and 24 dry flies with black bodies to match the hatch. Both men fished Pennsylvania's Cumberland Valley limestone streams, the Letort Spring Run, Big Spring Creek, Falling Spring Run, where gin-clear water and ultra-selective brown trout demanded a level of precision that most anglers of the era couldn't fathom.

Marinaro documented his Trico observations in In the Ring of the Rise (1976), one of the most influential books in dry fly fishing history. His detailed accounts of trout feeding behavior during spinner falls, the narrow feeding lanes, the rhythmic rise patterns, the instant refusal of any fly showing the slightest hint of drag, established Trico fishing as the ultimate test of angling skill. The "White-Winged Curse" nickname captured both the beauty and the frustration: white wings on the water as far as you can see, and not a single fish interested in your imitation.

The Trico hatch extended the useful dry fly season deep into summer and fall, when most other major hatches have ended. On tailwaters like the Bighorn, Missouri, and San Juan, Trico mornings became the signature event, the reason guides blocked out their entire August and September calendars.

The Patterns

The Trico Spinner (The Essential Pattern)

This is the fly you need. The spent spinner, wings outstretched, body flush in the film, is what trout eat during 90% of the spinner fall. Everything else is secondary.

The Trico Parachute (The Visible Version)

Same pattern but with an upright white wing post and parachute hackle. You can actually see this one on the water, which is the entire point. Use it as your "indicator" fly in a two-fly rig with a standard spinner dropper.

The Triple Trico / Cluster Pattern

During dense spinner falls, trout often feed by skimming, mouth open, moving through clusters of spinners rather than picking individuals. A cluster pattern imitates three or four spinners bunched together. Tied on a larger hook (#16-18) for visibility and hookup rate, with multiple wings and a slightly oversized body. Best when the fall is heaviest; switch to singles as it thins.

The Sunken Spinner

After the spinner fall, many Tricos sink just below the surface film. Fish that appear to be rising but refuse every surface fly are eating drowned spinners. A pattern tied on an emerger hook (2X short) with sparse wings and a slim body, fished just subsurface on 7X tippet, can be devastating when nothing else works.

Tying the Trico Spinner: Step by Step

The challenge with Trico patterns is not complexity, it's restraint. At sizes 22-24, every fiber matters. Bulk is the enemy. If you think you have the right amount of material, remove half.

Thread: Use 14/0 or finer. At #22-24, standard 8/0 thread builds too much bulk. UTC 70 denier works for #20; go to 32 denier for anything smaller.

Step 1: Thread base. Start thread behind the eye, wrap a smooth, even base back to the bend. This thread base IS your abdomen, don't plan to add anything over it.

Step 2: Tails. Select three white Microfibbetts. Tie in at the bend, splaying them into a fan with cross-wraps. Length should be approximately three times the hook length. Apply a tiny drop of head cement to the tie-in point for durability. The tails anchor the fly in the surface film and act as outriggers for stability.

Step 3: Abdomen. Wrap thread forward to the thorax area, about one-third of the shank length behind the eye. That's it. No dubbing. No tinsel. No anything. The thread IS the abdomen. For a male Trico, black thread creates the right color. For a female, switch to pale olive thread.

Step 4: Wings. Take a sparse bunch of white poly yarn or Zelon, and then take out half of it. Natural Trico spinner wings are nearly transparent. Your wings should be barely visible, not opaque white flags. Tie in on top of the shank at the thorax point. Use figure-eight wraps to separate the wings into a spent position, flat, extending perpendicular to the shank, 180 degrees apart. Each wing should be roughly one hook-length long.

Step 5: Thorax. Dub the faintest wisp of black Superfine dubbing around the wing base, building a tiny thorax hump. Cross-wraps around the wings help lock them in the spent position. The thorax should be barely larger than the abdomen, this is a tiny fly, and the proportions need to stay tiny.

Step 6: Head and finish. A few thread wraps behind the eye, whip finish, and a micro-drop of head cement. Done.

The entire fly should look like almost nothing on the hook. That's correct. If it looks "finished" by normal standards, it's probably too bulky for a Trico.

Fishing the Spinner Fall

Equipment

Rod: 3-weight or 4-weight, 8.5 to 9 feet. Light enough to feel the subtle takes, long enough to manage the long leader.

Leader: 12-15 feet minimum, tapered to 6X or 7X. Yes, 7X. The trout have stared at six thousand natural Trico spinners this morning, they notice everything. As one guide on the Bighorn put it: "If you're not losing flies to the occasional accidental break-off, your tippet is too heavy."

The double-dry rig: Tie a visible fly, a Parachute Adams or Trico Parachute in #16-18, as your lead fly. Drop a Trico spinner 12-16 inches off the bend on 6X-7X tippet. Watch the indicator fly. When it disappears or twitches, set the hook. You will almost never see the eat on the actual Trico.

Reading the Water

Don't cast blindly into the spinner fall. Pick a single fish. Watch its rhythm, three sips, pause, three sips, pause. Time the feeding interval. Calculate the drift speed. Then place your fly in the feeding lane so it arrives during the next rise cycle.

The rises are subtle. Look for tiny dimples, not splashy takes. Listen for the soft "smack" of a trout sipping spinners. A fish that barely dents the surface is almost certainly a big one, they're efficient feeders that barely move to eat.

The 68-Degree Rule

Carry a stream thermometer, not for the water, for the air. The spinner fall begins when air temperature hits approximately 68°F. In July, that might be 9 AM. In September, it might be 7:30 AM. Knowing when the fall will start lets you position yourself before the fish start rising.

After the Fall

Here's the secret that Trico mornings give you: the fish don't go down. After feeding on spinners for two hours, trout are surface-oriented for the rest of the day. Switch to terrestrials, a foam ant (#14-16) or a foam beetle (#16), and fish through the afternoon. Or try a sunken Trico spinner pattern for fish that are still eating drowned spinners just below the film.

Tom Rosenbauer specifically emphasizes this as one of the best things about a Trico morning, the fishing doesn't end when the hatch does.

Where to Find Them

The legendary waters:

Pennsylvania limestone creeks, The Letort, Big Spring, Falling Spring. Where it all started. Marinaro and Fox's laboratory. The most technical, the most selective, the most rewarding.

Bighorn River, Montana, July and August Trico spinner falls so dense they look like fog over the riffles. Every trout in the river rises.

Missouri River, Montana, Late July through September. Tricos are one of the Missouri's signature hatches.

San Juan River, New Mexico, Year-round midge and mayfly activity; Tricos add another layer in summer and fall.

Green River, Utah, August through September, particularly the lower sections. Dense Trico hatches combined with tiny BWOs create some of the finest small-fly fishing in the West.

South Platte River, Colorado, Deckers and Cheesman Canyon. Excellent Trico mornings from late July through September.

Video Tutorials

Charlie Craven's Trico Spinner: Charlie Craven: Trico Spinner Fly Tying Instructions, The master tier walks through the pattern step by step. Pay attention to how sparse he keeps the wings.

Segmented body technique: Barry Ord Clarke: Trico Spent Spinner with Moose Mane Body, A European take on the pattern using segmented moose mane for a realistic body. Beautiful close-up work.

How Many to Carry

For a standard Trico box: 6 male spinners (#22, black body), 6 female spinners (#22, olive body), 3 Trico Parachutes (#20, for indicator), 3 cluster patterns (#18), 3 sunken spinners (#22). That's 21 flies.

The materials are minimal, a spool of fine thread, a few Microfibbetts, a pinch of poly yarn, and the smallest dubbing in your collection. The flies take 2-3 minutes each at the vise. The challenge isn't the tying. It's the restraint. Less material. Less bulk. Less everything. The best Trico spinner is the one that looks like it might blow off the hook in a stiff breeze.

That's the one the fish eat.