Trout: How to Capitalize on the Hottest Last-Season Hatches

I used to spend a fair amount of time slinking around Montana during fall, searching for a brown trout of gargantuan proportions—one that stretched 30 inches or longer. I never caught that particular fish, but I did manage one measuring 27 inches, and I caught it on a 5-inch-long articulated streamer called the Sex Dungeon.

The Dungeon is one of Kelly Galloup’s most noted patterns—big and ugly and something I once thought necessary to catch brown trout during fall. It was only later that I learned you can take browns—and rainbows and cutthroats, too—while matching a variety of fall hatches, which are among the most productive of the entire year.

In many ways, matching those fall hatches is more rewarding than slinging half a chicken over your head all day. While it’s true you are less likely to catch a massive brown or rainbow on an emerger or a dry fly, what you sacrifice in size you can make up for in numbers. And you can do so during one of the nicest times of the year, when mornings dawn brisk and sometimes frosty, giving way to spectacularly warm afternoons and evenings.

BWOs and October Caddis

One of the most widespread and productive fall hatches is that of the blue-winged olive mayfly (BWO). These diminutive bugs, which are matched by size-18, 20 and 22 imitations, come off in droves most fall days, beginning in mid-September and building through October. The hatch can begin as early as 10 a.m., but it really pops in the afternoon, typically from noon or 1 p.m. through 4 or 5 p.m. Once you see bugs on the water and fish swirling at or just under the surface, it’s time to tie on an emerger or adult BWO imitation.

For my money, regardless of which mayfly you’re matching, you can’t beat emergers. These patterns imitate emerging, crippled and/or stillborn blue-winged olives. During a strong hatch, trout focus on those bugs instead of fully formed adults. Why, you ask? Because trout won’t expend more energy attempting to eat an insect than they can get in return, and compromised BWOs are easier to catch than adults.

Some of my favorite emergers are the classic Quigley Cripple, the Sparkle Dun, the Sparkle Spinner and Harrop’s Last Chance Cripple. If trout are being picky, make sure you downsize your fly. For instance, if they aren’t taking size-18s, go to a 20 or 22. If you’re matching adult blue-wings, try Parachute Adams, Comparaduns and Purple Hazes. Because rivers often run low and clear during fall, you’ll want to go with the lightest tippet possible, which means 5X or 6X. If the trout appear leader shy, lengthen your tippet by a couple feet or even consider 7X. Whether matching BWOs or any other fall hatch, always try to feed those trout with your fly ahead of the leader. Angled downstream casts are the ticket.

Look for fish holding in long runs or anywhere they can get relief from faster flows. They’ll post up behind rocks and logs, cruise the back eddies and feed along the inside seams of riffles. They’ll also hide between mats of grass, even in relatively shallow water.

Some of my favorite “olive” waters include Montana’s Missouri, Bitterroot and Clark Fork rivers. In Idaho I’ve enjoyed incredible days on the Gem State’s cutthroat waters, including the St. Joe, Lochsa and Kelly Creek. In the Yellowstone region, fall blue-wing hatches are super productive on the Madison and Firehole rivers.

Another great fall hatch—one that often happens in conjunction with the blue-winged olives—is the October caddis. These big, orangish-colored bugs are matched by size-8 and size-10 imitations. October caddis arrive by mid-September on most Western waters and remain on a trout’s menu through October.

One of the best tactics when October caddis are active, which is afternoons and early evenings, is to fish an Elk Hair October Caddis or an orange Stimulator with a smaller blue-winged emerger or adult trailing a couple feet behind. Sometimes trout take the caddis; other times they take the blue-wing, and the caddis serves as a very effective indicator.

Terrestrial Temptations

While summer is the season of the hopper, grasshoppers, along with many other terrestrial insects, make up a big percentage of a trout’s diet in September and early October. And some of those terrestrial options might surprise you as they did me one early-fall afternoon in Yellowstone National Park.

A friend and I had hiked in about 5 miles to reach a beautiful winding meadow stream known to hold some big rainbows. But nothing would touch our hoppers. When trout began rising steadily, we wondered, what are they eating? My friend climbed down a bank, reached out and grabbed a couple bugs off the surface. He took a quick glance and shook his hand violently. “They’re wasps!” he yelled.

I didn’t have any specific wasp imitations, but a couple ant patterns were close enough in configuration to do the trick. Those wasps weren’t on the water all day; when they were, however, we landed two rainbows over 20 inches and a few more in the 17- to 19-inch range. If you ever encounter that situation, make sure you have a couple Harrop CDC Water Wasps in your collection. You can thank me later.

You can count on grasshoppers being present on most western waters during late summer and early fall. The best time to fish hoppers is during the heat of the day, especially on windy days when big gusts blow grasshoppers out of the bankside grass and onto the water.

While grasshoppers represent a big meal, getting trout to eat hoppers isn’t always a slam dunk. In fact, quite often you’ll see a trout moving to your fly, only to bump it with its nose and turn away. You have to remember: It’s not like yours is the only grasshopper they’ve ever seen. By September and October, in fact, most trout have seen dozens of hoppers floating over their heads every day for a month or more.

There are two ways to approach this challenge. First, you can switch from a big, size-4 or 6 hopper to a size-8 or 10. That’s often the difference between eats and refusals. In addition, fishing a hopper that rests flush on the surface, versus one that’s tied with an abundance of hackle and rides super high, gives the fish more confidence. The tradeoff is that a hopper riding flush on the surface is more difficult to see than one riding high. Some of my favorite grasshopper imitations are Keller’s Henneberry Hopper, the Morrish Hopper and Trina’s Hopper.

Unfortunately, on some fall days it seems like the fish wouldn’t eat a hopper if their lives depended on it. When that happens, I often clip off the hopper, go to a lighter tippet in the 4X or 5X range and tie on an ant. I also employ an ant when I can’t get a particular fish to eat a mayfly or caddis dry. Quite often, an ant draws a take on the first cast even after you’ve swum a hopper, mayfly or caddis over a trout’s head 20 times. Some of my favorite ant patterns are Galloup’s Ant-Acid, Arrick’s Parachute Ant and the Para Ant.

My favorite way to fish terrestrials is from a drift boat or raft, banging hoppers and ants to the banks. Montana’s Yellowstone and Madison rivers offer this kind of experience, as do the Missouri, Clark Fork and Flathead rivers. In Yellowstone Country, Soda Butte, Slough and Pebble creeks provide great walk-and-wade terrestrial fishing, as do the Lamar and Snake rivers. In Idaho, the Henry’s Fork, South Fork Snake, Big Wood and South Fork Boise rivers offer great opportunity.

Trico Madness

Most fly-fishers have a love-hate relationship with tricos. This hatch offers some of the most exciting fishing of the year, but also proves very challenging to match, especially when your fly may compete for attention with a thousand naturals, all riding on the same 3- to 4-yard patch of real estate.

Female tricos emerge in the morning and join males that emerged the previous day. They form gigantic mating clouds, then both sexes fall to the surface as spinners. On a late-summer/early-fall morning, this activity begins sometime between 6 and 9 a.m. and may extend into the late-morning hours. Fish size-20 to size-24 trico dun and spinner imitations.

There’s an unwritten rule in Trico fishing: Don’t spook the pod! To avoid doing that you’ll need to cast gently, stopping your rod on the forward cast so the line, leader and fly fall gently to the surface. You’ll also need to employ that downstream/angled cast so a trout sees your fly before the tippet. Because tricos are so small, and the surface they ride is slick, you’ll need to go with 6X or 7X tippet.

Excellent patterns to match tricos include Parachute Tricos, Rusty Spinners, Sparkle Spinners and Biot Spinners. Sunken spinners are effective late in a hatch or spinnerfall, when drowned tricos float under the surface.

I started fishing tricos on Idaho’s Silver Creek back in the 1990s and loved the extreme challenge. You can still get that thrill on Silver Creek, along with Idaho’s Henry’s Fork. In Montana you can find them on the Madison within Yellowstone Park, along with Hebgen Reservoir, which rests just outside the park. The Missouri, Bighorn, Clark Fork and Bitterroot rivers also offer great Trico hatches.

Overall, fall may be the best time of the year to be on the water. Temperatures are cool but mostly pleasant, and trout are in peak condition. Fall hatches are some of the strongest of the year, and on any given day you could match mayflies, caddis or terrestrials. The opportunities are endless. And if you want those giant browns, fish that are mostly nocturnal during other times of the year, fall is the time to catch them, too … assuming you don’t mind hucking that big “chicken” over your head all day.

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