Threadline October Caddis: A Deadly Slim Profile for Big Fish

If you're a fly angler looking to up your game this fall, the Threadline October Caddis is a must-have in your fly box. Inspired by the proven effectiveness of Lance Eagan’s Thread Frenchie, this pattern marries simplicity with a slim, realistic profile to quickly dive into the feeding zone. The Threadline October Caddis is not just another nymph; it’s a game-changer, perfect for Euro Nymphing, drifting under an indicator, or as a dropper beneath a large dry fly. It’s time to build some anticipation because this deadly pattern could be your ticket to landing some of the best fish this season.

Why the October Caddis?

The October Caddis, also known as Dicosmoecus, is one of the largest caddisfly species, making it an irresistible meal for fish. Emerging in late summer through early fall, these robust insects are a key food source for trout and other species as temperatures begin to drop. When the water cools and these caddis start hatching, fish become highly attuned to their presence. The fluttering adults and their vulnerable pupal forms can spark intense feeding activity, making this the perfect time to capitalize on the hatch.

The Threadline October Caddis pattern mimics the pupal form of this insect, which is a critical stage in its life cycle when it drifts through the water column before emerging as an adult. This slim, fast-sinking pattern is ideal for reaching fish quickly, helping you present the fly at the perfect depth.

The Power of Simplicity: Why This Fly Works

The slim profile of the Threadline October Caddis plays off the Thread Frenchie’s success. Lance Eagan’s Thread Frenchie is a confidence fly—its simple design, slim profile, and ability to get deep quickly make it a consistent performer. The same principles apply here: the Threadline October Caddis uses minimal but effective materials to create a fly that doesn’t just look good but fishes even better. The thin body allows it to sink rapidly, while the subtle details perfectly mimic a caddis pupa, making it irresistible to fish feeding in the water column.

This nymph pattern is versatile. You can fish it on your Euro Nymph setup to stay in constant contact with the fly or under an indicator if you prefer a traditional nymphing rig. For those who love dry-dropper setups, it shines as a deadly dropper beneath a larger dry fly. Whatever your style, the Threadline October Caddis can easily be adapted to fit your approach.

Regional Hatch Chart for October Caddis

Knowing when and where to fish this pattern is key to success. Here’s a regional hatch chart to help you plan your next adventure:

United States

Pacific Northwest (Washington
, Oregon, Northern California):
Hatch Time: Late September to early November

Best Times of Day: Late afternoon to dusk

Conditions: Cooler, overcast days with water temperatures dropping below 60°F

Rocky Mountains (Idaho, Montana, Wyoming, Colorado):

Hatch Time: Late September through October
Best Times of Day: Midday to evening, especially on warmer afternoons
Conditions: Crisp, sunny fall days after a cold front, or cloudy days when fish are actively feeding

Northeast (New York, Pennsylvania, Vermont):

Hatch Time: Mid-October to early November
Best Times of Day: Late afternoon to dusk
Conditions: Overcast skies with light rain or just after a storm

Canada

British Columbia:

Hatch Time: Early October to early November
Best Times of Day: Late afternoon to evening
Conditions: Cloudy or rainy fall days, especially in slower-moving waters

Alberta:

Hatch Time: Mid-September through October
Best Times of Day: Midday to late afternoon
Conditions: Cooler, sunny afternoons with clear water

Europe

Western Europe (France, Germany, UK):

Hatch Time: Mid-September to early November
Best Times of Day: Late afternoon, particularly on warm, calm days
Conditions: Overcast skies or light drizzle, with steady, cooler temperatures

Scandinavia (Norway, Sweden):

Hatch Time: Early September through October
Best Times of Day: Late afternoon
Conditions: Windless days with overcast skies or just after a rainstorm
Best Times and Weather Conditions for Fishing the October Caddis
October Caddis hatches typically occur in the late afternoon and into the evening, making this the prime time to fish. On bright, sunny days, fish may not be as active in the middle of the day but will ramp up their feeding activity as the light fades. Overcast, cooler days, especially with light rain or cloud cover, can often spark more consistent activity, making it an ideal time to fish the Threadline October Caddis.

When targeting October Caddis hatches, focus on areas with moderate to slow currents, such as the edges of riffles or deeper pools where fish can comfortably feed. Look for cloudy days, as fish often feel more comfortable feeding closer to the surface under these conditions. In contrast, when the sun is bright, fish may stay deeper, and this is where the fast-sinking Threadline October Caddis can shine by getting into the feeding zone quickly.

Tie and Fish Your Own Threadline October Caddis

Tying the Threadline October Caddis is simple but effective. You can find all the materials you need at Moonlit Fly Fishing to craft your own. Using basic materials like thread, a tungsten bead, and a caddis-specific body, you’ll have a fly that’s both easy to tie and deadly on the water. Its slim design ensures it cuts through the water fast, giving you an edge when targeting trout feeding on October Caddis pupae.

This fall, don’t miss out on the opportunity to fish the Threadline October Caddis. Whether you’re exploring alpine streams in the Rocky Mountains or targeting larger fish in slower rivers, this pattern is versatile enough to fit a variety of waters and setups. With the materials in hand and the excitement of tying your own flies, you’ll be prepared for one of the most exciting times of the fly fishing season.

Gear Up and Hit the Water

Check out our Fly Tying Tutorial and Materials list below to pick up everything you need to tie the Threadline October Caddis. You’ll find tungsten beads, premium hooks, perfect threads, and materials to create your own deadly pattern. Don’t wait until the October Caddis hatches are in full swing—be ready to tie and fish this fly and make the most of this exciting season!

Adventure is calling. It’s time to fish your own Threadline October Caddis and experience the thrill of hooking into hungry, fall-feeding trout. Grab your materials, tie your flies, and hit the water!

Slimline October Caddis Nymph Fly Tying Tutorial

Slimline October Caddis Nymph Materials List:

• Hook: Moonlit Premium TOGATTA ML502 sz8-12
• Bead: Moonlit Slotted Tungsten Bead Metallic Coffee Brown
• Wire: Semperfli Lead Free Wire 0.3mm
• Thread: Semperfli Classic Waxed 6/0 Burnt Orange
• Rib: Semperfli Non Tarnish 0.2mm Fly Tying Wire March Brown
• UV Resin: Solarez Thin Hard Resin
• UV Pen: Moonlit Quick Dry Adjustable UV Pen
• Thorax: Moonlit Pine Squirrel Dubbing Rusty Brown
• Hot Spot Collar: Semperfli Classic Waxed 8/0 Fluoro Orange