Step into a fly shop near any well-known trout river in Montana, Idaho, and Wyoming and take a look in their fly bins. It won’t take long to figure out the favorite hatch of local guides and anglers. On the Henry’s Fork near Last Chance the bins are stocked with drakes and duns. On the Madison near the cowboy town of Ennis, fly shops never run out of stoneflies and caddis. For the Missouri and Bighorn Rivers, anglers anticipate the arrival of Pale Morning Duns followed by clouds of billowing tricos.
Hatches, and the rising trout that hopefully feed on them, are at the root of why we fly fish. Casting a dry fly to a rising trout is a core element of our sport. Like a bartender won't have a career it if they can’t shake or stir it, a fly fishing guide won’t last long if he or she doesn’t enjoy matching the hatch. And, for any angler who is devoted to fly fishing to rising trout or just wants to do it more often, we’ve created this list of the best hatches in the Rocky Mountain West…and where to find them.
Often the hatch with the most sex appeal, yet hardest to hit right. Salmonflies are in the stonefly family and on most rivers hatch at the tail end of snowmelt runoff. Timing for this hatch is paramount—arrive a few days early and the rivers are too muddy to fish, yet arrive a few days too late and the hatch has already moved upstream. But, time it just right and you’re likely to have some of the most exciting big fly-big fish fishing of the season.
Time Frame: May and June; sometimes as late as early July
Pale Morning Duns
This mayfly hatches on nearly every trout river in Montana, Idaho, and Wyoming. But, they are star of the show on the region's tailwater rivers. The Bighorn, Missouri, Henry’s Fork, South Fork of the Snake, and a few others are home to an abundance of Pale Morning Duns (PMD). Anglers often enjoy fly fishing during a PMD hatch as the insects often hatch in riffles, forcing the trout to be a tad more opportunistic.
Time Frame: June and July
Every trout river in the world is home to caddis. In fact, many anglers probably caught their first trout on a caddis pattern. Hatching throughout the year in a variety of species, it is safe to say always be prepared for this hatch. That being said, there are some unique hatches of this active insect. Montana’s Smith River is known for very prolific caddis hatches in mid and late June. This five-day and four-night floating and camping trip has fishing that is only matched by the spectacular scenery. Idaho’s Middle Fork of the Salmon is another well-known fishery and home to abundant hatches of caddis.
Time Frame: June through October
Best Kept Secret: Waters flowing out of Yellowstone National Park or Glacier National Park
Blue Winged Olives
Primarily a spring and fall season mayfly, hatches of Blue Winged Olives reward the diehard angler. Known to hatch on rainy or snowy days when the weather turns nasty, these small mayflies drift along the surface like tiny sailboats. The trout respond accordingly and if conditions are right—overcast skies and very calm winds—anglers seeking dry fly nirvana will find it during a Blue Winged Olive hatch.
Time Frame: September and October and March and April
Most Popular Rivers: South Fork of the Snake, Kootenay, Missouri
Terrestrials: Hoppers, Ants, and Beetles
Technically, these insects to do no hatch from the water. However, these land-dwelling insects often—and not voluntarily, mind you—find themselves on the water. Trout are opportunistic feeders and if there are enough grasshoppers, ants, or beetles on the surface of the water, fish will follow suit and feed on these land-based insects. Because a variety of sizes and shapes of terrestrials exist, fly fishing terrestrials is an exciting component of dry fly fishing for rising trout.
Time Frame: late July through September