South Holston River Hatch Chart: Month-by-Month Hatches, Fly Patterns, and Sizes (SoHo)
If you’ve spent any time fly fishing the South Holston River, you already know the truth: this river rewards anglers who pay attention to bugs. The SoHo is a cold, clear tailwater with dependable insect life almost every month of the year—which is exactly why a South Holston River Hatch Chart is one of the most useful tools you can bring (right alongside a thermometer and a long leader).
This guide breaks down what’s typically hatching each month, what to tie on to match it, and specific fly examples + size ranges you can build a box around.
Quick note: hatch timing shifts with water temps, flows, weather, and generation schedules. Use this as a dependable baseline—then let what you see on the water make the final call.
Why the South Holston River Hatch Chart matters
The South Holston stays cold and trout-friendly year-round thanks to bottom-release flows, which helps keep bug life active across seasons. That consistency is why you’ll hear anglers talk about:
- Midges basically all year
- BWOs during the cooler windows
- Caddis in spring and again through the warmer months
- The legendary Sulphur hatch that draws anglers from across the country
How to use this hatch chart on the water
Before we go month-by-month, here’s how we recommend using a hatch chart on a technical river like the SoHo:
- Check flows + generation first (it affects where trout feed and whether you’re wading or floating).
- Match size before color (especially midges, BWOs, and pressured Sulphurs).
- Fish the life stage trout are eating (nymph/larva vs emerger vs dun vs spinner).
- Dial presentation: long leaders, light tippet, slack, and drag-free drifts win here.
South Holston River Hatch Chart (Month-by-Month)
January: Midges + Winter BWOs (when conditions line up)
Primary insects
- Midges (year-round) size 20–24
- Blue-Winged Olives (BWO) size 18–22
Top fly patterns (sizes)
- Zebra Midge (20–24)
- RS2 (20–24) as a tiny emerger
- BWO Sparkle Dun (18–22) on mild afternoons
- WD-40 (18–22) as a BWO nymph/emerger
Best approach
- 2-fly nymph rig: midge pupa + tiny emerger
- If you see noses: go BWO emerger/dun with 6X–7X
February: Midges stay king + BWOs continue
Primary insects
- Midges 20–24
- BWOs 18–22
Fly picks
- Griffith’s Gnat (20–24) when clusters show
- CDC Midge Emerger (20–24)
- BWO Parachute (18–22)
- Pheasant Tail (18–20) as a general mayfly nymph
Best approach
- Slow seams, soft takes—set gently.
- When BWOs pop on cloudy days, the dry fly window can be short but excellent.
March: Caddis shows up + BWOs taper late month
Primary insects
- Early spring Caddis size 10–16 (typical early window)
- Midges 20–24
- BWOs 18–22 (early March)
Fly picks
- Elk Hair Caddis (14–16)
- X-Caddis (14–16)
- Green Caddis Larva (14–16)
- Soft Hackle Pheasant Tail (16–18) when fish key on emergers
Best approach
- If adults are fluttering, swing a soft hackle at the end of the drift.
- If it’s quiet: nymph caddis larva/pupa near riffle edges.
April: Black caddis + early Sulphur nymphs (yes, even before the big show)
Primary insects
- Small black caddis size 18–20
- Sulphur nymphs size 14–16
- Midges 20–24
Fly picks
- Black Elk Hair Caddis (18–20)
- Black Caddis Pupa (18–20)
- Sulphur Pheasant Tail / Sulphur Nymph (14–16)
- Split Case PMD-style nymph (14–16) as a Sulphur stand-in
Best approach
- Don’t rush to only dry flies—April is often a “nymph first, dry second” month until consistent surface activity starts.
May: The season turns on—Sulphurs begin + caddis stays in play
Primary insects
- Sulphurs size 12–18 (major window begins)
- Caddis 12–16
- Midges + occasional BWOs in weather shifts
Fly picks
- Sulphur Comparadun (14–18)
- Sulphur Sparkle Dun (14–18)
- CDC Sulphur Emerger (16–18)
- Light Cahill / Pale yellow mayfly patterns (14–16)
- Tan Elk Hair Caddis (14–16)
Best approach
- Carry all 4 stages: nymph → emerger → dun → spinner.
- If trout are bulging but not breaking the surface, it’s usually an emerger game.
June: Peak dry fly energy—Sulphurs + Tricos begin
Primary insects
- Sulphurs 12–18
- Tricos (noted as a key SoHo bug)
- Caddis 12–16
Fly picks
- Sulphur Parachute (14–18)
- Trico Spinner (20–24)
- Trico Dun (20–24)
- Tan X-Caddis (14–16)
- Sulphur Soft Hackle (14–16) for emergers
Best approach
- Early: Trico spinners on calm slicks.
- Late afternoon/evening: Sulphur duns/spinners can be the main event.
July: Still Sulphurs + Tricos + terrestrials become a real player
Primary insects
- Sulphurs 12–18
- Caddis 12–16
- Terrestrials (ants/beetles/hoppers along banks)
- Tricos (mornings)
Fly picks
- Trico Spinner (20–24)
- Foam Beetle (14–18)
- Flying Ant (16–20)
- Parachute Sulphur (16–18)
- Tan Caddis (14–16)
Best approach
- If the hatch is over but trout are still looking up, terrestrials can save the day—especially tight to grass lines and under overhangs.
August: Late-summer mix—smaller Sulphurs + terrestrials + midges
Primary insects
- Sulphurs continue through warm months
- Midges always available
- Terrestrials remain important
Fly picks
- Sulphur Comparadun (16–18)
- Spent Sulphur Spinner (16–18)
- Foam Hopper (10–14) on banks (when flows allow)
- Zebra Midge (20–24)
Best approach
- Think “small and clean” in low clear water.
- Spinner falls can get picky—bring good light and a fresh 6X.
September: Transition month—hatches thin, but opportunities stay
Primary insects
- Late Sulphurs still possible (season runs long)
- Midges + lingering caddis
- Terrestrials fade late month
Fly picks
- Sulphur emerger (16–18)
- Tan/olive caddis (14–16)
- Ant (16–20)
- Midge pupa (20–24)
Best approach
- This is a great “match what you see” month: keep it simple and stay flexible.
October: Fall fishing—BWOs start returning + Sulphurs can still show
Primary insects
- Sulphurs can run deep into fall
- Midges 20–24
- BWO season ramps as temps cool (next month is stronger)
Fly picks
- BWO nymph (18–22)
- BWO Sparkle Dun (18–22)
- Midge cluster (20–24)
- Sulphur spinner (16–18) if you still see them
Best approach
- Overcast fall afternoons can bring that classic BWO “lights on” moment.
November: BWOs return + midges (cold-weather precision time)
Primary insects
- BWOs 18–22 (late fall window)
- Midges 20–24
Fly picks
- BWO Parachute (18–22)
- BWO emerger (RS2/Film Critic style) (18–22)
- Black Zebra Midge (20–24)
- Griffith’s Gnat (20–24)
Best approach
- Trout can get ultra-selective. Clean drifts and subtle hooksets matter more than changing flies every 5 minutes.
December: Midges + BWOs (and the quiet reward of winter tailwater fishing)
Primary insects
- Midges 20–24
- Stoneflies 14-18
- BWOs 18–22 (early December)
Fly picks
- Midge larva/pupa combo (20–24)
- CDC Midge Emerger (22–24)
- BWO dun/emerger (18–22)
Best approach
- Fish slow, deep, and clean—or hunt for a short afternoon hatch if temps bump up.
The “Core Box” to build from (if you want a simple SoHo fly list)
If you only want 12 flies that cover a huge chunk of the year:
- Zebra Midge (20–24)
- Griffith’s Gnat (20–24)
- RS2 (20–24)
- BWO Sparkle Dun (18–22)
- BWO Parachute (18–22)
- Elk Hair Caddis (14–16)
- X-Caddis (14–16)
- Black Caddis Pupa (18–20)
- Sulphur Comparadun (14–18)
- Sulphur Sparkle Dun (14–18)
- CDC Sulphur Emerger (16–18)
- Trico Spinner (20–24)
Plan your hatch fishing like a guide
At Trophy Water Guide Service, the whole point is helping you show up with the right plan—because the SoHo is technical, the fish are selective, and the best windows don’t always last long. (That’s also why we fish year-round and focus on building repeat clients who come back season after season.)
If you want to fish the Sulphur hatch when it’s at its best, or learn how to read these bugs in real time, a guided day can shortcut years of trial and error.
Justin Shroyer
Justin Shroyer graduated from Appalachian State University with a degree in Environmental Biology and Ecology, and has been guiding the region since 2003. He loves stalking massive tailwater brown trout, and never ignores a good top water smallmouth bite. Not afraid to think outside the box, or float the unfloatable, Justin varies his methods and locations to consistently put his customers on top notch fishing. Justin founded TWGS in 2009, and currently resides year-round in Boone, NC with his wife and two kids.