Fly Fishing the Trico Hatch & Spinner Fall

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Louis Cahill Photography

One of the trout landed on the South Platte that day during the spinner fall. Photo Louis Cahill

The first major spinner fall that I ever witnessed and had the pleasure of fishing took place many years ago on the South Platte River in Colorado.

I’ll never forget the excitement I felt as I watched countless trico spinners floating downstream in the surface film. Never in my life had I seen so many bugs on the water. With one scoop across the surface of the water with my hand, I held dozens of tricos. I was so amazed by the density of bugs on the water that it put me in a frozen trance. Unable to wet a line, I remember thinking to myself, “This must be what fly fishing in heaven is like.” Growing up in the Southeast, I’d never seen a spinner fall of such magnitude. I’d only read about them in books. Looking back on that day now, I believe my reluctance to start fishing that morning had a lot to do with me just taking it all in, and appreciating the true beauty of nature at work. Only after I took the time to pay my respect to the bugs and wild trout, did I feel worthy enough to begin fly fishing such a beautiful place.

Once I started fishing, it only took a few presentations before I got my first hook up on a double trico spinner imitation. It was a hefty cutthroat trout, almost as big around as it was long. It’s belly looked like it was going to burst open at any moment from all the tricos it had previously eaten. I revived and released the beauty and for the next hour and a half, I enjoyed sight fishing to the largest concentration of trophy class trout I’d ever laid my eyes upon. In some instances, there were so many fish rising at once, I had a hard time deciding which rising trout I wanted to cast to. Every fish I landed that morning got bigger than the last. If you ever pulled me aside and asked if there was a time on the water that I’d want to relive if I had the opportunity, that hour and a half on the South Platte would be it, no questions asked.

If you haven’t had the pleasure of fly fishing a trico hatch or spinner fall, by all means, make a point to do so as soon as you can. On the streams and rivers where tricos are abundant, you can expect to start seeing them from mid-July through September. Once they make a presence, they will show up consistently every morning. Over the years I’ve fished several more trico hatches but none were as productive as my first encounter with the bug on the South Platte. Its apparent to me now, that day was totally a case of beginners luck. Everything went right that day. Trico hatches can be extremely challenging and frustrating to fish at times because there’s often such a large number of bugs on the water. Trout can become super selective and your flies can easily get lost in the crowd of naturals. The timing and accuracy of your presentations need to be spot on because trout tend to decrease the size of they’re feeding lanes (often only a couple inches) when there’s mats of bugs floating over the top of them. To increase your odds during a Trico hatch, try quietly closing the distance between you and the rising fish you’re targeting. Doing so, it will make it easier to land your fly in the tiny feeding lanes of the trout and you’ll also have less problems getting a drag free drift.

It also can really help to get on the water early, well before the action starts.

Female Trico duns will hatch first thing in the morning (males generally hatch the night before and are less important for anglers as they stage and wait for their female counterparts), providing less technical fishing for anglers (duns are eaten by trout one at a time, and since they are fewer and farther between than spinners, trout will move farther to eat your dun imitations). The Trico duns are sort of like the appetizer for the trout before the main entree, which is the Trico spinners. And just like we like to gobble up appetizers aggressively when they’re dropped on a plate in front of us, so do trout. Have both female dun imitations (body has olive shade) and Trico nymphs on hand, since fishing them together as a dry/dropper can be highly effective during the female Trico emergence. Once the Trico duns hatch, they’ll fly to the banks to molt in preparation for mating with the males, and that will start the count down for the spinner fall.

Low riding spinner patterns can be really hard to track during the presentation and drift. I like to use indicator and parachute style flies for my lead fly for this reason. I’ll then tie on a traditional spinner dropper (often a double spinner) that rides in the surface film and looks more realistic. If you’re a competent fly tyer, try tying up your Trico patterns on a TMC 2488 hook. It’s beefed up shank provides extra strength for fighting big fish but it’s two times shorter than your standard hook, which makes it perfect for tying size 20-22 Trico’s. It also has a very large hook gap which will help increase your hook up ratio and keep your fish from coming unbuttoned. Another trick I learned from fly fisherman that regularly fish Trico hatches is to fish spinner patterns below the surface (use small beads or wrapped wire for the Trico body for weight to get the flies down). Once the spinner fall begins to taper off, many trout will transition from feeding on the surface to below the surface, especially the larger trout. Although most of the floating spinners will be gone, there still will be a significant number of naturals drifting under the surface that either drowned or were sucked under by current during the initial spinner fall. The great thing about trout feeding subsurface on spinners is they will often be less spooky, less selective and much easier to execute a drag free drift with your weighted spinner pattern.

Try targeting the tails of riffles, if you the option during the hatch, not only because that’s where the spinners tend to congregate but also because a large portion of the fish will be setting up shop awaiting the easy pickings. The turbulent water form the riffles will also help mask your position and cushion the fly line when it lands on the water. Plus, the faster moving water will not allow as much time for trout to scrutinize your patterns. That being said, just about all water will hold fish and provide opportunities for anglers to catch trout when Tricos are on the water.New Zealand fly fishing guide Chris Dore recommends to fish eddies, smaller current lines and backwaters after the spinner fall begins tapering off as well. He says that those areas usually will hold duns and spinners a good while after the hatch or spinner fall has shut down.

As for rigging I prefer a 9 foot 5x nylon/monofilament leader. Then I tie 18 inches of 6x fluorocarbon tippet for my lead fly whether it’s a dun or parachute spinner pattern. I then tie 12″ of 6x tippet off the bend of the lead fly hook and tie on my weighted spinner pattern. Lastly, don’t just carry the standard black bodied trico patterns. I also stock cream bodied Trico patterns since most females turn this color shade after they’ve dropped their egg sacs.

For all you fly fishers out there that regularly fish the Trico hatch and spinner fall, please take the time to drop us a comment with your favorite patterns.

Keep it Reel,

Come fish with us in the Bahamas!

Kent Klewein
Gink & Gasoline
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6 thoughts on “Fly Fishing the Trico Hatch & Spinner Fall

  1. I’m an avid daily reader of the blog, but posting about tricos in early February seems like filler. Baetis, sure, but tricos?

  2. I’ve fished a lot of trico hatches, both in Montana and the Upper Midwest and it’s been my experience that once things get really rolling, you need to stop trying to imitate just one bug. The naturals start globbing together into little bunches. Believe it or not, a size 16 Renegade is my go to fly during a big trico event. I think to the fish it looks like a big wad of bugs all mashed together. Obviously, presentation is key, but I swear to you that fish will break their regular feeding rhythm to eat it. They won’t do that for single trico imitation no matter how it’s tied. By the way, thanks for this site. I really enjoy it.

  3. Just read this post. I came back yesterday from the Arkansas river tailwaters below Pueblo Dam in colorado… huge Trico spinner hatch – unheard of in January. I was looking for this exact post! There was one guy whose spinners had blue flash on the thorax…maybe uv resin… reason?

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