If you have gone fly fishing in Montana in late summer, you’ve likely experienced the epic (yet frustrating) trico hatch. One minute the river is calm, the next it’s covered in clouds of tiny black mayflies, with seemingly every trout in the river feeding like it’s an all-you-can-eat buffet. Arguably the most exciting part about this hatch is also the most frustrating: the bugs are small, and the fish get picky fast. Chasing trout on trico dry flies is all about slowing down, matching the hatch, and making the perfect drift… until it isn’t.

Truthfully, you can do everything right with trico dry-fly fishing and still come up short. That’s why having a wide selection of trico dry flies is crucial for finding success with these picky trout. These are our go-to trico dry-fly patterns for late summer in Missoula—available in our Missoula fly shop or our online fly shop.

1. RIO's King Splitsville Spinner

Most mayfly spinners are hard to see and don’t capture the natural proportions of real mayflies. Enter the Splitsville Spinner. Its intricate design splays the wings wide from the body, while stacked grizzly hackle splits them for extra buoyancy, increased visibility, and a lifelike profile. This trico dry fly fools big fish in technical conditions time after time.

2. Two-Wing Spinner

It’s not uncommon to see two tricos get stuck together during or after mating. Anglers often notice these doomed, ever-stuck pairs floating by on the water’s surface during a trico spinner fall. They present a bigger, juicier target for hungry trout. This is why the Two-Wing Spinner is so effective. Wary trout notice this fly as an easy meal and pick them out among hundreds of other insects.

3. RIO’s Slick Midge

Not originally intended for tricos, the Slick Midge has proven to be a highly effective dry fly for the most technical late-summer fishing. Featuring a bright white CDC post, the Slick Midge is easy to track in variable conditions and adds lifelike movement on the water’s surface. Tied on a barbless hook, it rides low in the surface film, fooling fish keyed in on emerging or spent tricos alike. It’s an ideal fly for tricking selective trout during those glassy morning spinner falls.

4. Christiaens’ GT Adult

Need a delicate yet highly visible mayfly imitation that looks like the real deal? Look no further than Christiaens’ GT Adult. This fly is a proven performer across various mayfly hatches. Designed to land softly, this easy-to-spot dry fly fools even spooky trout. The GT Adult mimics a mayfly emerging from its shuck and sits just below the surface film, perfect for targeting large trout feeding on crippled mayflies.

5. Gould’s Drowned Spinner

Gould’s Drowned Spinner imitates tricos the way trout love them best: easy, vulnerable, and irresistible. Drowned spinners are an often-overlooked but sneaky-good option when dry-fly fishing isn’t producing. Designed to mimic waterlogged trico spinners that have sunk below the surface, Gould’s Drowned Spinner is perfect for trout feeding just under the film. While many anglers prefer dries, sometimes they aren’t the best option during the trico hatch. Dropping a Gould’s Drowned Spinner under a dun or larger attractor (like a Purple Haze or an ant pattern) will fool fish just below the surface. When trout won’t touch your dry, this is the ace up your sleeve.

Trico fishing in late summer in Missoula fly fishing is truly a test of patience, skill, and sometimes luck. If you haven’t chased the trico hatch while late summer fly fishing in Montana, you’re missing out on one of trout country's finest fly-fishing experiences.