The Trico Mayfly

Tricos, or Tricorythodes, are small mayflies known for synchronized morning hatches and spinner falls.

The lifecycle begins with nymphs dwelling in the substrate of rivers, spring creeks, streams, and stillwater fisheries that are rich in vegetation. The females hatch in the early morning hours whereas males hatch much later in the day. They transform into duns that gather in clouds above the water. These adults mate in the air during the late morning and the spent females return to the surface to lay eggs.

This brief, intricate cycle occurs during the warm months of July through September, offering anglers precise yet rewarding challenges. The name "Trico" originates from the fact that they have three tails, which is different from most mayfly species of significance to fly fishermen.

Top 5 Montana Rivers for Fly Fishing the Trico Hatch

• Missouri River: Below Holter Dam, the Missouri River is a legendary destination for Trico hatches. This tailwater boasts consistent flows and prolific Trico hatches from July through early September. Focus on the flats and slicks near Craig, Montana where trout rise in rhythmic patterns to sip spent spinners.

• Big Hole River: Known for its stunning scenery and world-class dry fly fishing, the Big Hole River sections near Melrose and Glen are perfect for targeting Trico-feeding trout. Early mornings see dense clouds of duns, followed by spinner falls that bring the trout to the surface for a few hours. Expect low flows and “hoot owl” restrictions when this hatch is at its peak

• Bitterroot River: The Bitterroot River is legendary for its Trico fishing in its stretches between Hamilton and Missoula. Its calm glides and gentle currents provide ideal conditions for observing subtle rises and executing precise presentations. As the spinner fall fades, trout continue to feed on sunken spinners found in back-eddies and along heavy foam lines.

• Bighorn River: This cold-water tailwater in central Montana is home to one of the premier Trico hatches in the west. Males hatch near dusk and then join the females during the morning hours in towering clouds of undulating spinners. Anglers fishing the Bighorn River can expect Trico hatches from August through early October.

• East Gallatin River: The East Gallatin River, particularly near Belgrade and Manhattan, is a hidden gem for dry fly anglers during the dog days of summer. Trout line up along rip-rap banks and form feeding pods in the slow-moving pools once the spinner fall occurs

• Other Notable Montana Fishing Locations for Trico Hatches : Reservoirs like Ennis and Hebgen lakes are highly regarded among Montana anglers for their early morning Trico fishing. In western Montana, the lower Clark Fork River is home to localized Trico hatches on the sections downstream of the Alberton Gorge. Trico hatches are also significant in the lives of trout that inhabit the various spring creeks of Montana, including the world-renowned Depuy’s Spring Creek, near Livingston.

Top 5 Flies for the Trico Hatch

1. CDC Trico Spinner : A must-have for the spinner fall, this pattern imitates spent females with precision and sits flat in the surface film

1. Double Wing Trico Spinner : Ideal for mimicking the blankets of spent spinners late in the morning hatches.

1. Parachute Trico : The high-visibility post aids in tracking this tiny fly in slick water, use a hi-viz post for quick identification from the naturals.

1. Sunken Trico: This beaded spinner pattern works well throughout the hatch periods when very few duns or spinners are on the surface.

1. Black Tailwater Tiny : A deadly choice as a dropper pattern for pre-hatch conditions when trout feed on ascending nymphs.

Angling Tips for Fly Fishing the Trico Hatch

• Time Your Arrival: The Trico hatch occurs in the early morning hours, often beginning around sunrise. Plan to be on the water by dawn to take full advantage of both the hatch and the spinner fall.

• Presentation Technique: Anglers fishing the Trico hatch will need to execute precise presentations. Use long leaders (12-15 feet) and fine tippets (6X-7X) to achieve a drag-free drift that mimics natural insect behavior.

• Gear Selection: Presentation fly rods in a 9’ 5-weight are ideal as the Trico hatch draws large fish to the surface. The St. Croix Technica, Scott G Series, and Orvis Helios F are a few of our Montana fishing guides’ favorites for fly fishing in Montana during a late summer Trico hatch. Pair with a fly line with a long, front taper like the Elite Rio Technical Trout for delicate presentations.

• Late Summer Condtions : Trico hatches peak from mid-July through early September during the time of year when the rivers and streams are warm and run low. Trout activity is at its peak in the morning hours, but quickly wanes once the spinner fall is complete and water temperatures rise.

• Fish Subsurface Too : Use weighted nymphs that are dark in color and sized small (#18-#20) as a dropper below a hopper pattern for angling success when trout are rising sporadically.

Fly Fishing the Trico Hatch with Fins and Feathers Guide Service

Fishing the Trico hatch is a pursuit of precision and patience, and having an experienced Montana fishing guide can make all the difference. Fins and Feathers Guide Service, based in Bozeman, Montana, offers tailored guided trips that cater to seasoned anglers seeking some late summer match the hatch, dry fly fishing.

These trips start during the early morning hours and are typically finished shortly after lunch. Ennis and Hebgen lakes, along with the Beaverhead and Big Hole rivers, are the most consistent dry fly fisheries near Bozeman during August and early September.

Contact us to learn more about our late summer Montana fly fishing trips customized to the dry fly angler with intermediate or advanced fly-fishing skills. We have been outfitting fly fishing trips in Montana for over two decades and have the experience to build unique itineraries around the skills and interests of our guests. Reservations can be placed online, via e-mail, or by calling us at 1-406-468-5019.