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

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Other Food

Worms & Eggs

Oligochaeta / salmonid ova

Not a hatch, but reliably the highest-percentage drift in dirty water and behind spawners. Aquatic worms wash in when flows rise; eggs drift below redds in spring and fall.

Order

Other Food

Family

Various

Genus

Various

Hook

#12-16

Season · Peak Runoff and spawn windows

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

Worms & Eggs

Emergence Triggers

Water Temp

34–60°F

Flow

Rising or off-color water for worms; spawn timing for eggs

Light

Any

Water Type

Deep runs, below spawning gravel

Lifecycle

How Trout Eat It — Stage by Stage

Adult

Runoff and spawn

Fish a worm deep and heavy when the water comes up and colors. Swap to an egg below spawning gravel — and stay off the redds themselves.

Match It

San Juan Worm#12-16

$2.50

Egg Pattern#14-16

$2.50

Cross-Reference

Where This Bug Matters

Beaverhead River

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

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