Hendrickson
Ephemerella subvaria
Mayfly
- Peak week
- May 15 – Jun 5
- Intensity
- Heavy
- Time of day
- Afternoon
- Water temp
- 50–58°F · peak 55°F
Top flies
Hendrickson Parachute #12-14 · Red Quill Spinner #12-14 · Pheasant Tail Nymph #14
Hatch calendar
Rapid River hatch calendar.
- Freestone
- Catch and release / fly fishing only / trophy native brook trout
- brook trout
- wild
Some of the largest native brook trout in the country live in the Rapid — multi-pound wild brookies on dry flies in a remote, hike-in setting.
Verify with the agency before fishing
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 Maine Department of Inland Fisheries & Wildlife before each trip.
What's hatching now
May on the water.
Midge
Chironomidae spp.
Midge- Peak week
- Year-round
- Intensity
- Moderate
- Time of day
- Midday
- Water temp
- 32–60°F · peak 40°F
Top flies
Griffith's Gnat #20-24 · Zebra Midge #20-22 · WD-40 #20
Blue Winged Olive
Baetis spp.
Mayfly- Peak week
- Apr 25 – May 25
- Intensity
- Moderate
- Time of day
- Afternoon
- Water temp
- 45–55°F · peak 50°F
Top flies
Parachute BWO #18-20 · CDC Comparadun #18-20 · Pheasant Tail Nymph #18
Spring emergence
March Brown
Maccaffertium vicarium
Mayfly- Peak week
- May 25 – Jun 20
- Intensity
- Moderate
- Time of day
- Afternoon
- Water temp
- 55–65°F · peak 60°F
Top flies
March Brown Parachute #10-12 · Grey Fox Comparadun #12 · March Brown Nymph #12
Full year calendar
Twelve months on Rapid River.
Each row is a hatch species. Bar color = type, opacity = intensity, peak month outlined. The current month is highlighted on the timeline.
MayflyCaddisStoneflyMidgeTerrestrial· peak month outlined · intensity = bar opacity · current month highlighted
Hatch species on Rapid River
The bug calendar in detail.
Midge
Chironomidae spp.
MidgeMiddayWater-temperature trigger
30°F32–60°Fpeak 40°F80°F- Duration
- 52 weeks
- Also called
- Chironomids · Snowflies
Top fly patterns
- Griffith's Gnat #20-24
- Zebra Midge #20-22
- WD-40 #20
- Disco Midge #22
Year-round food source — the only consistent option on tailwaters in winter. On cold sunny days look for noses sipping clusters in slow water.
Blue Winged Olive
Baetis spp.
MayflyAfternoonWater-temperature trigger
30°F45–55°Fpeak 50°F80°F- Duration
- 6 weeks
- Also called
- BWO · Olive
Top fly patterns
- Parachute BWO #18-20
- CDC Comparadun #18-20
- Pheasant Tail Nymph #18
- RS2 #20
Most reliable Eastern hatch. Two emergences — spring (March-April) and fall (September-October). Best on overcast, drizzly days.
Hendrickson
Ephemerella subvaria
MayflyAfternoonWater-temperature trigger
30°F50–58°Fpeak 55°F80°F- Duration
- 3 weeks
- Also called
- Red Quill · Dark Hendrickson
Top fly patterns
- Hendrickson Parachute #12-14
- Red Quill Spinner #12-14
- Pheasant Tail Nymph #14
- Hendrickson Comparadun #14
First substantial mayfly hatch on most Eastern rivers. Spinner falls in evening can be as productive as the dun emergence.
March Brown
Maccaffertium vicarium
MayflyAfternoonWater-temperature trigger
30°F55–65°Fpeak 60°F80°F- Duration
- 4 weeks
- Also called
- Grey Fox · American March Brown
Top fly patterns
- March Brown Parachute #10-12
- Grey Fox Comparadun #12
- March Brown Nymph #12
Sporadic emergence rather than a heavy hatch — but trout key on individual large duns drifting through. Freestone-river specialty.
Sulphur
Ephemerella dorothea / invaria
MayflyEveningWater-temperature trigger
30°F55–68°Fpeak 62°F80°F- Duration
- 6 weeks
- Also called
- Pale Watery · Little Yellow May
Top fly patterns
- Sulphur Parachute #16-18
- Sulphur Comparadun #16-18
- Sulphur Sparkle Dun #16
- Pheasant Tail Nymph #16
- Sulphur Spinner #18
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.
Light Cahill
Stenacron / Leucrocuta spp.
MayflyEveningWater-temperature trigger
30°F60–72°Fpeak 65°F80°F- Duration
- 5 weeks
- Also called
- Cahill
Top fly patterns
- Light Cahill Parachute #14-16
- Cahill Comparadun #14
- Light Cahill Spinner #14
Pale yellow-cream mayfly. Less intense hatch than Sulphur but reliable across many Eastern rivers in late spring through early summer.
Tan Caddis
Hydropsyche spp.
CaddisEveningWater-temperature trigger
30°F58–72°Fpeak 64°F80°F- Duration
- 10 weeks
- Also called
- Spotted Sedge · Cinnamon Caddis
Top fly patterns
- Elk Hair Caddis #14-16
- X-Caddis #14
- LaFontaine Sparkle Pupa #14
- Tan Caddis Soft Hackle #14
Workhorse summer caddis. Heavy emergences and egg-laying flights at dusk through summer. Drop a soft hackle on the swing during the evening.
Slate Drake
Isonychia bicolor
MayflyEveningWater-temperature trigger
30°F55–70°Fpeak 62°F80°F- Duration
- 12 weeks
- Also called
- Iso · Mahogany Dun (spinner)
Top fly patterns
- Slate Drake Parachute #12
- Iso Comparadun #12
- Mahogany Spinner #12
- Iso Nymph #12 (swimming nymph)
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.
Terrestrials
(beetles, ants, hoppers)
TerrestrialAfternoonWater-temperature trigger
30°F60–78°Fpeak 70°F80°F- Duration
- 12 weeks
- Also called
- Hoppers · Ants
Top fly patterns
- Foam Hopper #10-12
- Foam Beetle #14-16
- Para-Ant #16-18
- Chernobyl Ant #10
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.
River info
- River type
- Freestone
- Primary species
- brook_trout · wild
- Management
- Catch and release / fly fishing only / trophy native brook trout
- Counties
- Oxford County
- Elevation
- 1450 ft
- Access
- Remote — typically accessed by boat across Lake Umbagog or hike-in from the south. Section between Lower Richardson and Lake Umbagog is the famous water.
Sources
Data quality: estimated
Live water temperature & hatch alerts.
Bield Fish reads USGS gauges, watches for the trigger window, and pings you when Rapid River hits the temperature for your target hatch.
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