Few of the choices we make on the water feel more consequential than picking the right fly. It’s a choice that depends on too many variables to count.
The ideal fly type, pattern and size depend on the size of the river you’re fishing, the species of trout you expect to catch, and what—if any—insects are hatching at the moment. The wind, sunlight, time of day and water level all come into play.
Here in Idaho, stocking your fly box starts with what part of the state you plan to fish. From the legendary Eastern Idaho waterways like Henry’s Fork to northern Panhandle rivers like the Clearwater, wet and dry fly fishing starts with looking at the local conditions.
Regions in Idaho Fly Fishing
There are a few ways to divide the state of Idaho into regions and not a lot of agreement on where, exactly, the boundaries lie. Idaho Fish & Game splits the state into eight regions, but for simplicity’s sake, let’s consider Idaho in four parts—Eastern, Southwestern, Central and Northern—and take a closer look at the best fly patterns in each.
Eastern Idaho
If any part of Idaho could claim to offer the best fishing, it’s Eastern Idaho. This region’s reputation rests primarily on the Upper Snake River and its tributaries, including the Blackfoot River, South Fork Snake River, Teton River and—perhaps most legendary of all—Henry’s Fork. This is the only part of the state where Yellowstone cutthroat trout reside.
Many Eastern Idaho rivers support a May hatch of Grannom Caddis, sometimes referred to as the “Mother’s Day Hatch,” which can be imitated with a size 14 Peacock Fluttering Caddis or Royal Elk-Hair Caddis fly. Salmonflies emerge around the same time, and chunky dry flies that resemble these big bugs are essential through July.
Various mayfly and caddis species hatch throughout the region, and a selection of flies including Elk Hair Caddis, Adams, Blue Winged Olive, Pale Morning Dun will do a good job imitating most of them. Nymphs including Pheasant Tail, Hare’s Ear, Copper John and Zebra Midge are also essentials.
Southwestern Idaho
Although it is the most arid portion of Idaho, the southwest still offers some excellent fly fishing opportunities. The Boise River harbors large wild brown trout, while its South Fork is better known for rainbows. Reservoirs like Cascade Lake and Payette Lake provide a mixed bag of species including lake trout.
Zebra Midges and Pheasant Tails in sizes 16 to 20 are all-around good choices for nymphing in Southwestern Idaho. The South Fork Boise River has a major Pink Albert hatch in summer, and a size 16 Emerger pattern is killer for imitating the insects as they rise off the bottom. Size 6 and 8 Royal Stimulators nicely mimic various stoneflies and the cicadas that hatch here in June. Try a Sculpin pattern for big brown trout.
Central Idaho
Idaho’s most rugged and mountainous region is the central part of the state, including the Bitterroot Mountain Range. This area’s core artery is the Salmon River. Along with its South and Middle Forks and many, many smaller tributaries, the Salmon River offers tremendous fishing for species including Westslope cutthroat trout and bull trout.
Assorted caddis species hatch on and off from late spring to early fall and can be ably imitated with a Elk Hair Caddis or CDC Caddis in sizes 14 to 18. Trout often key in on purple patterns on the Salmon River system, making Purple Haze and Hippie Stomper patterns local favorites. Nymph fishing options include small beadhead Pheasant Tails and red Copper Johns.
Terrestrials, including hoppers, beetles and ants are always on the menu during summer. A Fat Albert or Chubby Chernobyl can imitate grasshoppers as well as the various stoneflies that hatch on Central Idaho streams. Choose one with some yellow when Golden Stoneflies and Yellow Sallies hatch in June and July.
Northern Idaho
Also known as the Panhandle, Northern Idaho is the place to fish if you really want to get away from it all. For our purposes, let’s consider Northern Idaho to be part of the state north of the Clearwater River. That includes the excellent St. Joe River, Kelly Creek and the Coeur d’Alene River. Bull trout are more common than in any other part of the state.
Northern Idaho rivers like the St. Joe have dependable mayfly hatches in early summer, including Pale Morning Duns, Blue-winged Olives and Green Drakes that can be imitated using size 18 to 18 Parachute fly patterns in the appropriate colors. In summer, beetle and ant patterns are often the most effective. For the bull trout that lurk in deep, cold pools on many Northern Idaho rivers, try streamers like a Muddler Minnow or Zonker in sizes 4 to 8.
Essential Flies for Idaho Fly Fishing
Certain fly patterns earn their place in any fly box, no matter what part of Idaho you’re fishing. These are some of the best all-around fly patterns that can lead to success on virtually any river in Idaho.
Dry Flies
- Parachute Adams (size 12-20) – One of the most popular flies in the world, a great bet when trout aren’t picky and there isn’t an active hatch going.
- Chubby Chernobyl (size 6-14) – A highly buoyant large terrestrial. It’s a great choice any time stoneflies are hatching, and it can also resemble a grasshopper.
- Elk Hair Caddis (size 10-18) – Arguably the number one caddis imitation, it can mimic a range of caddis and smaller stonefly species depending on the size.
- CDC Caddis (size 10-18) – Another excellent caddis for dry fly fishing, with extra buoyancy compared to the classic Elk Hair Caddis.
- Fat Albert (size 6-12) – similar to Chubby Chernobyl, this fly looks enough like any large bug with lots of legs that it can easily pass for a grasshopper, stonefly or cicada.
- Compara-Dun (size 16-24) – Can resemble virtually any mayfly species with slight color variations.
- PMX (size 10-14) – A highly buoyant and eye-catching attractor fly, especially good in off-color water
Nymphs
- Pheasant Tail Nymph (size 10-18) – An exceptionally versatile beadhead nymph that can look like a wide range of aquatic insects. Great when fished on a dropper beneath a dry fly.
- Hare’s Ear Nymph (size 10-18) – Offers lots of flash with a gold bead head, great for catching trout’s attention in stained water.
- Prince Nymph (size 8-16) – Great for spring nymph fishing, larger sizes are well-suited to imitating stonefly nymphs.
- Zebra Midge (size 16-22) – Highly versatile, a top pick in the midge category.
- Pat’s Rubber Legs (size 8-12) – An excellent stonefly nymph imitation, available in a wide range of colors.
- Copper John (size 12-20) – Can mimic any nymph, but especially mayfly nymphs. It’s flashy and heavy for its size, getting down near the bottom quickly.
Streamers
- Wooly Bugger (size 8-12) – A classic for big trout in large waters, it looks like nothing in particular, but everything in general: stonefly nymph, sculpin or leech depending on the size and color.
- Muddler Minnow (size 6-12) – Perfect imitation of sculpins and other native baitfish, ideal for bull trout and large brown trout.
- Zonker (size 4-8) – White, olive and black versions of this large, sleek streamer can be used to imitate various baitfish as well as leeches and crayfish.
San Juan Worm (size 10-12) – Difficult to categorize, this fly is great for wet fly fishing in springtime when worms are most often washed into rivers and streams.