Hatch-chart pattern list
Best Flies for Flathead River South Fork (Montana)
The Flathead River South Fork in Montana fishes as both a wade and a float. It is a freestone fishery for Westslope Cutthroat Trout and Bull Trout, with the most reliable window in July, August, September. The patterns below are matched to the hatch chart we publish for this water. They are not a live report of what other anglers caught this week.
This is not a live report of other anglers' catches. Presence and flow live on the Flathead River South Fork river page and the Montana destination guide.
What's hatching now
Month, insect, size, and pattern from the Flathead River South Fork hatch chart. August is highlighted when that month exists in the chart. We do not invent a hatch that is not on the chart.
| Month | Insect | Size | Pattern |
|---|---|---|---|
| January | Midge (Chironomidae) | #20-26 | Zebra Midge |
| February | Midge (Chironomidae) | #20-26 | Zebra Midge |
| March | Midge (Chironomidae) | #20-26 | Zebra Midge |
| April | Midge (Chironomidae) | #20-26 | Zebra Midge, Griffith's Gnat |
| Blue-winged Olive (Baetis) | #18-22 | Parachute BWO, RS2 | |
| May | Blue-winged Olive (Baetis) | #18-22 | Parachute BWO, RS2 |
| Caddis (Trichoptera) | #14-18 | Elk Hair Caddis, X-Caddis | |
| June | Golden Stonefly (Hesperoperla) | #6-10 | Golden Stone Dry, Pat's Rubber Legs |
| Pale Morning Dun (Ephemerella) | #16-18 | PMD Sparkle Dun, PMD Comparadun | |
| Caddis (Trichoptera) | #14-18 | Elk Hair Caddis, X-Caddis | |
| July | Salmonfly (Pteronarcys californica) | #4-8 | Sofa Pillow, Rogue Foam Stone, Pat's Rubber Legs |
| Golden Stonefly (Hesperoperla) | #6-10 | Golden Stone Dry, Pat's Rubber Legs | |
| Pale Morning Dun (Ephemerella) | #16-18 | PMD Sparkle Dun, PMD Comparadun | |
| Caddis (Trichoptera) | #14-18 | Elk Hair Caddis, Goddard Caddis | |
| Terrestrials | #8-12 | Hopper, Foam Beetle, Ant | |
| August | Terrestrials | #8-12 | Hopper, Foam Beetle, Ant |
| Caddis (Trichoptera) | #14-18 | Elk Hair Caddis, X-Caddis | |
| September | Blue-winged Olive (Baetis) | #18-22 | Parachute BWO, RS2 |
| October Caddis (Dicosmoecus) | #8-12 | October Caddis, Stimulator | |
| Terrestrials | #8-12 | Hopper, Foam Beetle, Ant | |
| October | Blue-winged Olive (Baetis) | #18-22 | Parachute BWO, RS2 |
| Mahogany Dun (Paraleptophlebia) | #14-16 | Mahogany Sparkle Dun | |
| November | Midge (Chironomidae) | #20-26 | Zebra Midge, Griffith's Gnat |
| December | Midge (Chironomidae) | #20-26 | Zebra Midge |
Nymphs
Subsurface patterns matched to this river's chart and catalog. Fish them at the size the chart lists, not the size that looks good in the bin.
Dries
Dries and terrestrials for the Flathead River South Fork. If the chart says a size 18 PMD, do not start with a 12.
Streamers
Streamers and wets for stained water, banks, and low light. This is not a claim that streamers are "on" today.
No catalog patterns in this group yet. Use the hatch chart and the river guide.
Setup
4X and 5X cover most nymphing. 4X on dries until the fish get picky, then 5X. A 3.0–3.8mm tungsten on the point and a lighter dropper is a default until you see the water. Tight-line the near bank and the heads of pockets. Use an indicator only when you need to search water you cannot euro.
FAQ
- What flies work on the Flathead River South Fork?
- Start with Zebra Midge and Griffith's Gnat, then match size to the hatch chart for the month you are standing in. The Flathead River South Fork does not need a 40-pattern box. It needs the right size on the insect that is actually in the drift.
- When is the best time to fly fish the Flathead River South Fork?
- The editorial window we list is July, August, September. That is a planning month range, not a guarantee. Shoulder months can fish well if flows and water temperature cooperate.
- Do I need a guide on the Flathead River South Fork?
- Montana has walk-up wade water and, on some sections, float water. A guide is worth it for a first float or a technical tailwater. A hatch chart and a gauge are enough for a first wade if you already nymph. We list local guides and shops on this page when we have them.
- Where can I see live flow for the Flathead River South Fork?
- Open the Flathead River South Fork river page for the USGS gauge, access notes, and the same hatch chart this fly list is built from. We do not publish other people's spots or fish counts.
- Is this a report of what's working now on the Flathead River South Fork?
- No. Executive Angler does not publish other anglers' catches, GPS, or a crowdsourced hot fly. This page is hatch-chart patterns plus catalog flies. Presence on the river page is gauge and weather only.
Related
River guide
Flathead River South Fork
Access, hatch chart, USGS gauge.
Destination
Montana
Trip planning for this region.
Pattern
Zebra Midge
Midge
Pattern
Griffith's Gnat
Dry
Pattern
BWO Sparkle Dun
Dry
Fly shop
Arrick's Fly Shop
37 Canyon St, West Yellowstone, MT 59758
Fly shop
Beartooth Flyfishing
2925 US-287, Cameron, MT 59720
Nearby water
Beaverhead River
Open the river guide, then its fly list.
Nearby water
Big Hole River
Open the river guide, then its fly list.
Nearby water
Bighorn River
Open the river guide, then its fly list.
Nearby water
Bitterroot River
Open the river guide, then its fly list.