Pattern Feeding: Fishing Spinner Falls Successfully Means Understanding Trout Feeding Rhythms

Affiliate Disclosure: This page contains affiliate links. We earn from qualifying purchases.

---

One of the most exhilarating experiences in fly fishing is being surrounded by a swarm of mayflies slowly falling to the water before you. their descent often leads to them being eaten, and a pod of trout frantically eating insects always reminds me of the game Hungry Hungry Hippos—the trout are trying to gulp down all the marbles.

While the sight of a spinner fall brings hope and promises a successful outing, this isn’t always guaranteed. Sometimes, precision alone isn’t enough–understanding the feeding behavior of the trout is key. This “pattern feeding” is crucial to your success.

When trout stop selectively targeting one insect at a time, they begin to scavenge the water’s surface with their jaws open, inhaling multiple insects in one go. It’s a true smorgasbord! This pattern feeding frenzy brings to mind one of my favorite books, Sex, Death, and Fly Fishing by the late, great John Gierach. If you were a mayfly, this could be renamed Sex, Death, and the Jaws of a Trout. It’s a short lifecycle that provides essential nourishment for the fish.

I vividly remember my first encounter with this grazing feeding behavior when I was 13 years old, fishing Elevenmile Canyon with my brother Sean. We had left early to beat the hatch and fish the top 2 miles of the South Platte River. This river was a catch-and-release haven. The setting was ideal: a bluebird sky on a warm summer morning in the early days of July.

At 9 A.M., the sky was filled with Tricos descending toward the water. As I waited for the fish to rise, I heard the sounds of gulping. To my astonishment, this wasn’t just a few fish but a pod of rainbows, cutthroats, and brown trout—all aggressively feeding. Each fish would rise three or four times and then rest briefly. I didn’t comprehend it then, but now I realize that this was my introduction to pattern feeding—a concept rarely discussed in books or articles. Pattern feeding provides one of the most exhilarating and rewarding dry-fly opportunities an angler can experience.

The Mayfly Menu

Mayflies are reliable because they often hatch in large numbers and they provide low-energy/high-success food items for trout. Long hatch cycles during spring, summer, and fall afternoons and evenings provide essential food sources for trout.

The mayfly lifecycle is magical. They begin as eggs on the river or lake bottom. These eggs hatch into nymphs, which live as aquatic insects for up to several years, depending on species and habitat. At hatch time, the nymphs crawl to shore or swim toward the surface. Once they reach the surface, they break out of their exoskeletons and metamorphose into winged adults. During this “stuck-in-the-shuck” transformational stage, they are particularly vulnerable to hungry trout because they can’t escape.

A few hours later, the duns shed their skins again, transforming into spinners. This stage exists because mayflies cannot achieve sexual maturity in one leap. The easy way to tell duns from spinners is that duns have dull, opaque wings while spinners have clear translucent wings.

When spinners mate, males and females fly over the water’s surface to find each other. After mating, the females fly down to the surface to lay their eggs. Once the eggs drop to the riverbed, male and female spinners fall to the water with their wings outstretched.

A large spinner fall can trigger the trout into some of the most intense pattern-feeding behavior an angler can experience.

Prime Lies

When spinners are plentiful and the trout are pattern feeding, they don’t necessarily pick out specific targets. Instead they take up a rhythmic feeding behavior that is more tuned to location and timing.

Each trout finds a specific feeding spot where it suspends itself about 2 to 6 inches below the surface, usually in prime spots where dead and dying mayflies coat the water like a blanket. My favorite locations are eddies, where the water swirls gently along the river’s edge; grassy banks that provide shelter; and soft riffled runs at the heads of pools, where fish can move easily from deeper water into the shallows. Such areas make it easy for the trout to feed while hiding from other predators that would try to eat them.

While surface feeding, a trout tilts its head upward, rotating its pectoral fins to allow the current to lift it to just beneath the surface. The trout then opens its mouth and gills, creating a vacuum to suck in numerous spinners with each gulp. This rapid, efficient feeding behavior allows trout to consume dozens of insects at a time.

It’s essential to look for subtle signs when trout are pattern feeding, especially with large fish that excel at being subtle—that’s how they evade predators. Sometimes you’ll see a glint of light reflecting off the fish’s nose, or a small dimple on the water’s surface. Occasionally, a trout’s feeding pattern becomes so refined that it vacuums in the spinners while remaining completely below the surface, making it hard to detect.

Trout may feed once, then rest for a few seconds. Or they may gulp two or three times sequentially and then rest for longer periods. Each spinner fall and every trout presents its own timing and patterns. It’s important to focus less on your fly pattern and more on the trout and what they are doing. Timing your cast so your fly lands at the right spot at just the right moment is often the most critical factor.

Student of the Game

Whenever I observe rising trout, I think of a quote from Vincent Marinaro’s In the Ring of the Rise, which I bought decades ago in a used bookstore. Marinaro discusses the importance of observing trout rise forms to understand their feeding behavior. He notes that “a bubble left in the ring of the trout’s rise indicates that the fish took an insect off the surface.”

This observation helps anglers determine whether the fish are feeding on the surface or subsurface, guiding them in selecting the appropriate fly patterns.

When a trout takes insects from the surface, it creates a splash or ripple. Look for a bubble or precise, distinct rise forms, such as the trout’s head breaking the surface or a smooth, circular ripple.

At times—particularly when a hatch is just starting or after the peak of a spinner fall—you may encounter trout feeding just under the surface. If the rise is more subtle, and you see only a slight bulge or a quiet ripple, the trout is likely taking emergers or spinners just below the surface.

By closely observing the rise forms, you can adjust your fly choice to match what the fish are feeding on, whether it’s a dry fly like a Rusty Spinner or Parachute Adams for surface feeders or a nymph or emerger for subsurface trout. Sometimes, when pattern feeding at the surface slows down or stops, subsurface feeding is just picking up.

I was fishing with a client one day during a heavy Trico spinner fall on the South Platte River. Trout had been rising steadily, but the fishing slowed and we hiked downstream below some structure in the river channel that acted as a natural weir.

I didn’t spot any rises, but I could see that trout were darting around in the pool, feeding heavily on something below the surface. It occurred to me that the spent Trico spinners from upstream were being pushed underwater when they went over the weir. The subsurface trout were picking them off as if they were nymphs.

I set up an indicator-style nymphing rig for my angler, with an unweighted Trico spinner imitation as the point fly. The trout, we quickly discovered, were still feeding heavily, just under the surface. Days later, I tied a similar fly pattern on a heavy-wire hook with a sparse spentwing and a wire abdomen so that it would sink through the surface film.

Some days it worked, but other days it didn’t. It got down to where the fish were feeding but the problem was the yarn wings, which were originally meant to help float the fly.

If you look at any natural spinner wings, you’ll see they have beautiful markings resembling stained glass. And like glass, they are all transparent, not a solid opaque color. If you tie a spinner with poly yarn wings or another material that does not transmit light, the fly immediately forms a silhouette that does not appear natural.

This led me to design my Tails Up Trico dry fly in sizes 18 to 22, and my subsurface Sink It Spinner in sizes 14 to 22—in colors that match Pale Morning Dun, Blue-winged Olive, and Trico spinners. I cut the wings for the Tails Up Trico from clear plastic sandwich bags. For the Sink It Spinner wings, I use 1/8-inch Umpqua Scud Back, a heavy Tiemco 2488 hook, and a plastic or brass bead.

Rigging the Sink It Spinner

I use Scientific Anglers Absolute Trout Stealth leaders in green-tinted nylon. The tint reduces reflection, and is less likely to spook the fish. To the leader, I attach 18 to 24 inches of fluorocarbon tippet. Fluorocarbon has a refractive index similar to water, so it’s almost invisible to fish. It’s also abrasion-resistant, making it great for both wary trout and tricky terrain with rocks, deadfalls, or other structure. While fluorocarbon does sink, the thin tippet stays on top while you’re using small dry flies. When I fish a weighted fly like a Sink It Spinner, fluorocarbon helps get it under the surface a little quicker.

I use micro-swivels between the nylon leader and the fluorocarbon tippet for durable, stealthy connections. This helps reduce line twist when I’m casting or fishing in swirling currents. It also creates a smooth transition between the different materials, particularly when I’m stepping down in tippet size. Another benefit is that a micro-swivel extends the leader’s life, since you can replace tippet sections without shortening the entire setup. Using a 25-pound-test micro-swivel, I tie the “stealth” nylon leader to one end and the fluorocarbon tippet to the other, ensuring a seamless transition while maintaining a natural drift.

I pinch on a small piece of Loon Outdoors Biostrike indicator material about 2 feet above the swivel. Sometimes I tie on two Sink It Spinners. If fish are rising, I forgo the indicator and tie an indicator dry fly to the fluorocarbon tippet. Then I tie on the Sink It Spinner as a dropper.

Combining tinted nylon leaders, fluorocarbon tippet, and micro-swivels ensures stealthy, durable, and effective presentations that will fool even the most selective, cautious trout.

However, a stealthy leader doesn’t help if you are not stealthy yourself. Even when fish are feeding on floating and drowned spinners, trout are still wary of predators. Even the most subtle movements can alert them to your presence.

Keep a low profile and move slowly to avoid disturbing the water. Position yourself at the water’s edge at a low angle to make it less likely for the fish to spot you, as opposed to standing tall and casting from a high vantage point.

Before casting, take the time to study the water. Observe the flow patterns, how the water moves past the fish’s feeding lane, and any surface disturbances that could indicate where the trout are feeding. By paying close attention to these details, you can more accurately predict where to cast.

I prefer to cast from behind and off to one side of the fish, at an angle that keeps the leader butt and fly line away from the trout. A down-and-across presentation can work in some situations, but you’ll have to cast farther to stay out of the trout’s field of vision.

Cast the fly 2 or 3 feet upstream of the fish, aligning your cast so the fly drifts directly into the trout’s feeding zone. After the fly lands, immediately mend the line upstream to create some slack and reduce drag. With a sunken spinner, you may see the fish swirl, you may see a tail or dorsal fin, or you might see just the white wink of the trout’s mouth. Often there is only a subtle movement of the leader, or the line may just go tight. Strike gently with these little flies—it takes very little pressure to pull the hook into the corner of the trout’s mouth.

Whether you are mimicking a spent spinner on the surface or underwater, good timing, accurate casting, and a realistic fly and presentation will set you up for success. With these tools, you’ll be well on your way to solving what can be an exciting but sometimes frustrating situation. Spinner falls can produce frenzied feeding, but also hyperselectivity.

Trico Recipes

Tails Up Trico

• HOOK: #18-22 Tiemco 101.
• THREAD: Olive 8/0 UNI-Thread.
• TAILS: White Microfibetts.
• LEGS: Black #18-20 Metz dry-fly hackle.
• WINGS: 2mm clear plastic.
• THORAX: Black Super Fine Dry Fly Dubbing.

Sink It Spinner

• HOOK: #14-22 Tiemco 100.
• BEAD: Brass or plastic bead, 3/32, 5/64, or 1/16 inch.
• THREAD: 8/0 hopper yellow, olive, or black.
• TAIL: Light Cahill, dun, or white Microfibetts.
• HACKLE: Brown, gray, or black #18 Whiting Farms.
• WINGS: Dark gray, yellow, or white 1/8-inch Umpqua Scud Back.
• THORAX: Light Cahill, dark olive dun, or black UV Dubbing.

---

Landon Mayer is a fly-fishing guide and Fly Fisherman contributing editor. He lives in Woodland Park, Colorado. His video Landon Mayer: Guide Flies and Other Favorites is available on Vimeo through Headwater Media Group.

---