Photo by Les Korcala

Trico Overview

  • Species: Mayfly
  • Size: 4-6mm (18-20)
  • Emergence: Early August through Mid September
  • Emergence Time: 8:0 AM to Noon

The Trico hatch in Montana truly catches the angler’s imagination. Coming in late August when there is little insect activity around Missoula, the Trico moves a lot of the fish in the river to feed. It’s a realistic time to try and join the 20/20 club- a 20” fish on a size 20 fly!

Tricos are one of the few mayflies that have identifiable male and female stages. The males are dark olive to black in the abdomen, while the females have a white abdomen. Compounding this, the adults emerge at the same time as the spinners fall. You now have adult males and females, as well as male and female spinners. Add cripples and emergers, and you have one of the most complex hatches in the Montana.

Fly Fishing The Trico

There are different ways to approach the trico hatch. One is to pick a pattern, and show it to as many fish as you can. The other way is to pick a fish and change flies till you find what it’s eating. Due to the insect’s small size, feeding fish prefer slow water for feeding, so the Clark Fork River and Bitterroot River have better Trico fishing than the Blackfoot River and Rock Creek. Not that there are no Tricos on the latter, just fewer places where fish rise to small mayflies.

Tricos are one of the few mayflies that thrive in sunshine. That applies a lot of pressure to the angler. You’ll need to stretch your leader out to the finest tippet you’re comfortable with, at the longest length you’re comfortable with. We recommend Trout Hunter tippet, which is much softer than other tippet materials, and allows the Trico to float more naturally.

When To Fish The Trico

Trico Hatch On Missouri River

This hatch is prolific and will last from the first week in August through mid-October depending on temperatures. That means the fish are very familiar with this insect, so your imitation needs to be very accurate, and moving naturally. Your leader is almost as important as the fly when it comes to fly fishing the Trico hatch.

The Trico will hatch as early as 8:00 am in the morning, and typically will go till noon around Missoula. You’ll know when the hatch is about to start, as the spinners will begin to swarm in their unique figure 8 flight path above the water. You can watch the cloud of Tricos drop, and when they hit the water, it’s game on! This is a hatch worth seeking out.

MAngler Exclusive Fly Pattern

Ron Beck, our longest employee working at the shop since the late 80’s, has designed a trico pattern the shop and Missoula fly fishing guides have found deadly. We also fish a lot of comparaduns through this hatch, because it can mimic adults and spinners.

Additional Trico Resources