by daryl gadbow
photo by michael gallacher (on_the_fly.jpg)

During the early years of my fly-fishing evolution, one of my neophyte companions generically referred to any hatch of especially small flies as “itty-bitties.”

In his parlance, itty-bitties was a label of scorn and, to us, it was code for fly-fishing futility.

As in, “How’d you do?”

“Oh, not worth a darn. They were feeding on itty-bitties.”

In later years, I learned that from midsummer on into the fall, our frustration with itty-bitties often was attributable to encounters with hatches of a genus of tiny mayflies known as Tricos, short for Tricorythodes.

Ultimately, I discovered that it’s well worth the time and effort to develop a strategy for fishing the Trico hatch on western Montana rivers.

In the 1970s, I began to approach fly-fishing more seriously. I pored over all the fly-fishing literature I could get my hands on. In the pages of some of the latest magazines, I came across articles about how the experts take on the challenge of Tricos.

At first, I was skeptical of these scholarly missives. They discussed the use of spiderweb-fine leader tippets of 7X and nearly microscopic imitations in sizes 22 and 24.

I remember thinking at the time, “Why bother with such puny tackle?” Any trout worth messing with, I concluded, could be enticed with a size 8 hopper, a size 2 muddler, a fat woolly bugger, or if the fish were inordinately finicky, my old secret weapon – a size 14 royal Wulff. After all, those patterns represent trout meals that seem far more substantial and satisfying than some dinky mayfly.

Anyway, I figured even if a fish can see a size 24 fly, it would take an eagle-eyed angler to track one on the water.

Shortly after that, however, I changed my tune on Tricos.

One August morning while jogging along the Bitterroot River on the edge of Missoula, I paused on a high bank to watch fish rising on a long flat stretch. They were feeding eagerly, lined up like hogs at the trough, just bulging the surface in rhythmic gluttony.

Obviously, a major hatch was in progress, but from my elevated perch, I couldn’t see any flies.

I assumed the subtle rise forms, in such slow flat water, were made by a school of whitefish. But as I observed them more carefully through my polarized glasses, I was able to discern the fish finning just below the surface. They were all trout. Walking quietly along the bank, I counted a couple of dozen rainbows feeding in a 30-yard section of the flat.

What really excited me, though, was the size of the fish. They ranged from 12 inches to well over 20, with a preponderance of them tending toward the upper end of that scale.

When I knelt at the edge of the river to see what the trout were gorging on, I noticed that the surface was peppered with minuscule black-bodied mayflies, with delicate silvery wings. They floated spread-eagle on the water and collected by the thousands in solid mats in eddies and foam lines in the current. I recognized them from my reading as Tricos.

Countless more of these dainty mayfly spinners danced up and down in shimmering clouds, their mating swarms hovering just over the surface in the morning sun.

I was back on the stream the next day, armed with a 7X tippet on my fly rod and the closest imitations I had – some size 20 mosquito patterns.

The trout were slurping away on schedule. But the extremely calm, clear water made approaching within easy casting range of the fish a bit tricky. I spooked the first few fish with sloppy casts.

Eventually, I discovered that the most effective presentation of a fly to these persnickety trout was a downstream drift, letting the fly land softly several feet above a bulging rise and feeding slack line so that it floated directly down to the trout’s feeding station.

I learned that the trout would shy away if there was the lightest unnatural drag on the fly, or if the leader passed over the fish ahead of the fly. If the presentation was off-line more than about six inches to the side, it inevitably was studiously ignored.

This was, indeed, tough fishing. And it got tougher.

That first day, I managed to hook five rainbows. And five straight times the fish snapped my 7X tippet, either when I set the hook or on their first jump.

Frustrated, but determined to solve this fishing predicament, I came back the next day. This time I tried a slightly thicker 6X tippet, which is about 3-pound test, and had better luck. Using as much restraint as I could muster to set the hook gently, I netted a couple of rainbows between 14 and 16 inches. Still, I had one larger fish break the line the first time it cartwheeled out of the water.

For the next few weeks, up until the middle of September, I continued to fish the Trico hatch on the Bitterroot and Clark Fork rivers. And I continued to experiment with my tackle and technique.

Gradually, I increased my tippet size to 5X, and even 4X, while also trying larger, size 18 imitations. I was pleased to find 5X – about 4-pound test – was a successful compromise of thickness and strength, as long as I employed a downstream drift presentation.

Trout feeding on Tricos will take a size 20 imitation more readily than a size 18. But, for me, the hook-holding advantage of the 18s outweighs the occasional refusals.

In more recent years, I’ve refined my Trico tactics even further.

These days, my imitation of choice is a “double Trico” that I tie on a size 16 hook. The pattern is essentially two size 20 tricos tied one behind the other, with just fine black thread for each separate body, and for wings, high-quality grizzly dry-fly hackles – one spun sparsely at the eye of the hook and the other about in the middle, between the two bodies. Tricos have prominent, split tails, so I tie in a few splayed white or dun hackle fibers at the bend of the hook.

The pattern is surprisingly easy to tie. And the size 16 hook gives me added confidence when playing large trout, with a bonus of being easier to see on the water. Sometimes I trim the hackle on the bottom to make the wings float flush on the water and look more realistic. But I don’t think it’s necessary.

I have a friend who ties a “triple Trico” pattern on a size 12 hook. But I think that may be overdoing it.

The downstream drift presentation I prefer for Trico fishing is definitely easier from a boat than when wade fishing.

Local guides often assist their clients fishing the Trico hatch by tying a tiny mayfly imitation – either a dry or a very small nymph – on a dropper below a hopper or other large buoyant bug. I can vouch that this trick works … at least sometimes.

And, fortunately, sometimes those super-selective trout will even deign to take the hopper.

Another little ruse I employ as a fall-back measure for fooling temperamental Trico sippers is a size 18 royal Wulff. The combination of peacock herl, red floss, and white wing sets this offering apart from the parade of black-and-silver Tricos and seems to grab a trout’s attention often enough to be effective. It might suggest a small ant or other terrestrial insect. For whatever reason, this ploy seems to work particularly well on the lower Clark Fork.

The best Trico fisherman I know is Bob Meseroll, the Missoulian’s sports editor, who also is a regular contributor of fly-fishing articles to the newspaper as well as this magazine. But Bob initially honed his fly-fishing skills on the highly discriminating trout and ultra-difficult spring-creek-like conditions of the Henry’s Fork of the Snake River in Idaho. And he ties exquisite imitations – both the dun and spinner variations – of Tricos and other flies. He’s got an edge on most of us.

But some of the little stratagems I’ve mentioned here have definitely helped me take advantage of one of the greatest late-season fly-fishing opportunities in western Montana – the Trico hatch.

It’s not the easiest fishing, but at least now I’m not so intimidated by the dreaded “itty-bitties.”

Daryl Gadbow is a former Missoulian reporter, now a full-time fisherman and occasional free-lance writer. Michael Gallacher is a Missoulian photographer. He can be reached at (406) 523-5270 or by email at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .