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.

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Terrestrial

Spruce Moth

Choristoneura freemani

The western spruce budworm moth. In outbreak years it showers off timbered banks through August and freestone trout gorge on it — a caddis-shaped hatch that comes from the forest rather than the river.

Order

Terrestrial

Family

Tortricidae

Genus

Choristoneura

Hook

#12-14

Season · Peak Aug

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

Spruce Moth

Emergence Triggers

Water Temp

52–66°F

Flow

Late-summer base flows

Light

Warm mornings and evenings

Water Type

Timbered banks, riffles below conifer stands

Lifecycle

How Trout Eat It — Stage by Stage

Adult

Aug, mornings and evenings

Fish tight to timbered banks and the riffles just below them. A tan caddis-profile dry with a twitch covers it; the takes are splashy.

Match It

Spruce Moth#12-14

$3.15

Elk Hair Caddis#12-14

$2.95

Cross-Reference

Where This Bug Matters

Big Hole River

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

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