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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Mayfly

Hatching Now

Trico

Tricorythodes explicatus

Tiny black-and-white mayflies that fall in clouds on summer mornings. The spinner fall — not the hatch — is the event: thousands of bugs, pods of sippers, 7X tippet.

Order

Mayfly

Family

Leptohyphidae

Genus

Tricorythodes

Hook

#20-24

Season · Peak Jul-Sep mornings

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

Trico

Emergence Triggers

Water Temp

58–68°F

Flow

Low, clear summer flows

Light

Calm, sunny mornings — falls when air hits about 60F

Water Type

Slow flats, weedy tailouts

Lifecycle

How Trout Eat It — Stage by Stage

Nymph

Overnight-dawn

Rarely worth imitating — the payoff is on top. A small black midge covers it.

Match It

Zebra Midge#20-22

$2.50

Dun

Dawn

Duns emerge at first light and molt within the hour. A short pre-game before the main event.

Match It

Trico Dun#20-22

$3.15

Spinner

Mid-morning fall

Fish sip in steady rhythm. Time your cast to the rise cadence; a cluster pattern saves eyesight.

Match It

Trico Spinner#20-24

$2.95

Double Trico#18

$3.25

Cross-Reference

Where This Bug Matters

Henrys Fork

August spinner clouds at Wood Road 16

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

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