Sulphur
Ephemerella dorothea / invaria
- Peak week
- May 20 – Jun 25
- Intensity
- Heavy
- Time of day
- Evening
- Water temp
- 55–68°F · peak 62°F
Top flies
Sulphur Parachute #16-18 · Sulphur Comparadun #16-18 · Sulphur Sparkle Dun #16
Hatch calendar
Medium-sized Blue Ridge freestone with native brookies in the upper reaches and stocked rainbows below. Reliable freestone hatch progression.
Fishing regulations change every season. This page is a summary maintained by Bield — bag limits, exact dates, and species-specific rules must be verified with Rose River Farm before each trip.
What's hatching now
Ephemerella dorothea / invaria
Top flies
Sulphur Parachute #16-18 · Sulphur Comparadun #16-18 · Sulphur Sparkle Dun #16
Chironomidae spp.
Top flies
Griffith's Gnat #20-24 · Zebra Midge #20-22 · WD-40 #20
Baetis spp.
Top flies
Parachute BWO #18-20 · CDC Comparadun #18-20 · Pheasant Tail Nymph #18
Spring emergence
Epeorus pleuralis
Top flies
Quill Gordon Dry #12-14 · Quill Gordon Wet #12 · Pheasant Tail Nymph #14
Ephemerella subvaria
Top flies
Hendrickson Parachute #12-14 · Red Quill Spinner #12-14 · Pheasant Tail Nymph #14
Brachycentrus spp.
Top flies
Elk Hair Caddis #14-16 · Henryville Special #14-16 · LaFontaine Sparkle Pupa #14
Maccaffertium vicarium
Top flies
March Brown Parachute #10-12 · Grey Fox Comparadun #12 · March Brown Nymph #12
Full year calendar
Each row is a hatch species. Bar color = type, opacity = intensity, peak month outlined. The current month is highlighted on the timeline.
Hatch species on Rose River
Chironomidae spp.
Water-temperature trigger
Top fly patterns
Year-round food source — the only consistent option on tailwaters in winter. On cold sunny days look for noses sipping clusters in slow water.
Baetis spp.
Water-temperature trigger
Top fly patterns
Most reliable Eastern hatch. Two emergences — spring (March-April) and fall (September-October). Best on overcast, drizzly days.
Epeorus pleuralis
Water-temperature trigger
Top fly patterns
Classic Catskill spring hatch. First major mayfly of the year on many freestone streams. Emerges underwater — wet flies often outperform dries.
Ephemerella subvaria
Water-temperature trigger
Top fly patterns
First substantial mayfly hatch on most Eastern rivers. Spinner falls in evening can be as productive as the dun emergence.
Brachycentrus spp.
Water-temperature trigger
Top fly patterns
First major caddis emergence of the year. Look for clouds of small dark caddis above riffles in late afternoon.
Maccaffertium vicarium
Water-temperature trigger
Top fly patterns
Sporadic emergence rather than a heavy hatch — but trout key on individual large duns drifting through. Freestone-river specialty.
Ephemerella dorothea / invaria
Water-temperature trigger
Top fly patterns
The most important mayfly hatch on Eastern rivers. Reliable emergence + spinner fall every evening for 4-6 weeks. Match the spinners with rusty-bodied patterns.
Stenacron / Leucrocuta spp.
Water-temperature trigger
Top fly patterns
Pale yellow-cream mayfly. Less intense hatch than Sulphur but reliable across many Eastern rivers in late spring through early summer.
Isoperla spp.
Water-temperature trigger
Top fly patterns
Common on freestone rivers. Adults flutter back to lay eggs on warm afternoons — trout target the egg-laying females.
Hydropsyche spp.
Water-temperature trigger
Top fly patterns
Workhorse summer caddis. Heavy emergences and egg-laying flights at dusk through summer. Drop a soft hackle on the swing during the evening.
Isonychia bicolor
Water-temperature trigger
Top fly patterns
Long-running hatch from June into October. Nymphs are strong swimmers and crawl out of the water to emerge — fish a swung wet fly through riffles.
(beetles, ants, hoppers)
Water-temperature trigger
Top fly patterns
Not a hatch but the most important summer trout food in many Eastern systems. Fish tight to grassy banks and overhanging trees. Hopper-dropper rigs are deadly July through September.
Pycnopsyche spp.
Water-temperature trigger
Top fly patterns
Large orange-bodied caddis. The big fall food source on cold freestone rivers. Trout eat them all day in October but the egg-laying flight at dusk is the most explosive feeding.
River info
Bield Fish reads USGS gauges, watches for the trigger window, and pings you when Rose River hits the temperature for your target hatch.
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