Trico Time in Montana

My Lab Flicka sitting on a rock in the middle of the river keeping an eye on the action

It’s mid-morning and the pool of water below the riffle looks calm. It looks calm but looks can be deceiving. The surface of the water is calm but the mayhem is about to start.

While I don’t see any fish rising I tie on a small dry fly and cast it out on the water. There’s a dimple on the water’s surface and I tighten the line; a nice fish is on the other end and it’s not at all happy about that little hook in the corner of its jaw. After a short but splashy fight I draw the fish up close so I can unhook it and send it back to the water.

For the last couple weeks I’ve been spending time on the Big Hole River following the trico hatch, that late summer blizzard of tiny mayflies that get the trout in a brief feeding frenzy just about every morning.

The trico, short for Ttrichorythodes, is tiny but prolific. As is the case with most aquatic insects, that last stage of life as an adult flying insect is brief. The bug emerges from the water in the early morning hours and in the next few hours will change from a dun to a spinner, breed in mid-air in a swarm of many thousands of bugs and then return to the water to lay eggs and die. At that point its mission in life is complete. It became an adult flying insect and procreated.

The insects feed the fish in all its life forms but it’s that final stage, the spinner fall, which triggers the feeding frenzy, though there was a time when fly anglers occasionally looked at the trico hatch as the “white curse” because they really hadn’t come to an understanding of this tiny bug and how to fish for trout during the trico season.

The sheer numbers of flying insects in the air is more than most of us can imagine. Swarms of tricos fly over the river in a visible cloud. Gusts of wind will scatter the swarms and it’s almost like a snowstorm.

On this particular morning at 10:30 the mating swarms hadn’t shown up yet but the fish were waiting and eager to nibble on anything small and dry. While I unhooked that first fish I could see some tricos in the air and at the same time I could see the rings on the water’s surface where fish were sipping in the little bits of protein. As they got into it there were rises all over the pool, with splashy rises becoming common as the trout got caught up in the moment.

On that last weekend in August I fished the same pool on two successive mornings and on the first morning I caught mostly rainbow trout. The second morning I caught mostly brown trout. Of course it’s hard to fish the trico spinner fall without catching whitefish. Whitefish really seem to love sipping in those tricos and sometimes it’ll seem as if there are nothing but whitefish in the river. On an earlier weekend I fished another stretch of the Big Hole and whitefish, along with a few yearling grayling, furnished almost all of the action.

On some waters trout are notoriously selective about taking flies that are a close match to the real thing. That means flies that seem almost microscopic, especially for those of us well advanced into the bifocal generation. Personally, I find tying flies on #24 hooks more trouble than it’s worth, and trying to thread the end of my tippet into the eye of the hook almost impossible.

On the Big Hole, at least, I can usually get away with using larger flies, if you call a fly on a #18 hook large. On this particular morning I started with a standard #18 Adams. After several fish the fly looked pretty tattered but as long as it floated it caught fish.

Elk and upland birds are taking over the spotlight right now, but don’t forget the trout. There’s a lot of fun going on.

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