Sign In Sign Up Free

River Intelligence · Entomology

Read the Water. Match the Hatch.

Every river has an entomological fingerprint — the bugs it grows, when they hatch, and how trout eat them. Learn the bugs, cross-reference live flows, and fill your box before you go.

Hatching NowPale Morning Dun Green Drake Trico Sulphur Small Western Red Quill Flav Gray Drake Callibaetis Spotted Sedge Golden Stone Yellow Sally Brown Drake Pink Lady Terrestrials Scuds & Sowbugs

Encyclopedia Hatch Calendar River Fingerprints Match the Hatch Bug School

Entomological Fingerprints

Each river grows a different insect community. The barcode is 12 months of total hatch biomass — no two rivers match.

Beaverhead River

Pumphouse to State Bridge · CO

Caddis-dominant biomass with strong golden stones; mayflies play a supporting role. Warm summer temps push hatches to mornings and evenings.

Deschutes River

Warm Springs to Maupin · WA

Early stonefly calendar (runs about three weeks ahead of Montana), heavy caddis biomass, and a famous October Caddis finale.

Railroad Ranch (Harriman) · ID

Mayfly-dominant spring creek. Silt and weed beds grow crawler and swimmer mayflies in absurd density; stoneflies matter only on the canyon edges.

Quake Lake to Ennis · MT

Stonefly-dominant freestone. Biomass skews to big Pteronarcys and Hesperoperla in fast cobble; caddis carry summer; Baetis shoulder-season.

Yellowstone River

Paradise Valley · MT

Classic big freestone: stonefly and caddis biomass, late runoff compresses the dry-fly season into an intense July-October window.

≋ Waterlands · Hatch data blends USGS gauges, NOAA temps & regional emergence records

USGS Real-time Data · Free to Start · No Credit Card