Waterlands
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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Stonefly
Hatching Now

Yellow Sally

Isoperla mormona

The little yellow stonefly everyone under-fishes. Sallies dribble off all summer, and a small yellow dry through riffle water is quietly one of the best searching flies in the West.

Order
Stonefly
Family
Perlodidae
Genus
Isoperla
Hook
#14-16
Season · Peak Jun-Aug
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Yellow Sally
Emergence Triggers
Water Temp
55–65°F
Flow
Summer base flows
Light
Afternoons and evenings
Water Type
Riffles, gravel runs
Lifecycle
How Trout Eat It — Stage by Stage
1
Nymph
Jun-Aug

Slim yellow nymphs crawl shoreward in the shallows. A small gold-ribbed nymph as a dropper covers them.

Match It
Yellow Sally Nymph#14-16
$2.95
Hare's Ear#14
$2.75
2
Adult
Summer afternoons

Egg-laying females dip and flutter over riffles — fish a yellow dry with a red butt through choppy water.

Match It
Yellow Sally#14-16
$2.95
Yellow Stimulator#14
$3.25
Cross-Reference
Where This Bug Matters
≋ Waterlands · Hatch data blends USGS gauges, NOAA temps & regional emergence records
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