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Stonefly

Salmonfly

Pteronarcys californica · species

A huge spring stonefly whose migrating nymphs and egg-laying adults bring trout to the banks.

Overview

About Salmonfly

Pteronarcys californica is the giant salmonfly, a large western stonefly in the family Pteronarcyidae and one of the most important hatch-matching insects in fly fishing. Its long aquatic life and dramatic shoreline emergence make both nymphs and adults high-value trout food.

Also known as: Giant Stonefly

Life Cycle

Eggs

Female Salmonflies deposit thousands of eggs on the water's surface. These eggs then sink to the river bottom, settling among rocks.

Nymph

Salmonfly nymphs reside among rocks and submerged debris in the river, where they feed and grow for one to four years.

Mature Nymph

As nymphs mature and approach emergence, they typically migrate towards the river banks, often under the cover of night or in the early morning hours.

Emerger

The nymph crawls out of the water onto rocks or streamside vegetation. Here, it sheds its exoskeleton to transform into an adult.

Adult Salmonfly

Newly emerged adult Salmonflies rest to allow their wings to dry and harden before they can take flight.

Mating Adults

Adult Salmonflies mate in the air near the river or within streamside vegetation.

Egg Laying Female

After mating, female Salmonflies return to the water to deposit their eggs, thus restarting the life cycle.

Stages: Anglers mainly fish the nymph and adult. Nymphs live in the river for roughly three to four years before crawling out to emerge; adults then mate, and females return to deposit eggs.
Emergence cues: Look for emergence in spring as water warms, especially when mature nymphs collect in shallow edges and on nearshore rocks. Adult activity often builds on warm days, with egg-laying adults returning over the water later in the hatch.
Behavior: Late in development, nymphs migrate from midriver toward the shoreline, making them especially vulnerable before they crawl out on rocks or bankside structure to emerge. Adults are clumsy, fluttering insects, and females may fall or skate during egg laying.

How to Tie Salmonfly Patterns

Nymph

Tying the Soft Hackle Salmon Fly Nymph - Dressed Irons

Dressed Irons

Materials

Tiemco 200R#6Hook
Danville Thread70 DenierBlack
Lead Wire.020optional
BiotBlack, Turkey or Goose (Tail)
Round Vinyl RibLargeBlack
Life Cycle DubbingBlack (Abdomen)
Rayon ChenilleMediumBlack (Thorax)
Collard Brown HackleLegs

Mature Nymph

Jig Salmonfly Nymph

Danie Erasmus (pgflyfisher)

Materials

Hooksize 6
Hanak 400BLsize 6or Sierra BL Barbless hook
Tungsten bead4.6 millimetergunmetal
Threadsize 6black
Lead wire0.0254X area
Uniflexblack detector uniflex

Emerger

The Only Salmonfly Pattern You Need This Spring- Mothership Salmonfly: Dry Fly Tying Tutorial

Caddis Fly Angling Shop

Materials

Ahrex 570 Dry LongSize 4
Semperfli Nanosilk Black50D
Hareline 2mm Hi Float FoamOrange
Antron DubOrange
Hareline 1mm Ultra Thin Fly FoamBlack
Hareline WebwingMedium Dun
Copic MarkersPale Sepia, Blue, Copper
Loctite Brush On
Montana Fly Company Widow’s WebGrey

Adult Salmonfly

Slammin Fly I AJ Ties a Very Buoyant Salmon Fly | Fly Tying Tutorial

Fly Fish Food

Materials

u680 streamer hooksize 6
Semper Fly thread6/0 fluorescent orange
Foamfor body
Zap-A-Gapglue to secure fly
Sharpiefor wing stripes

Fly Patterns

Chubby Chernobyl#6-12
Pat's Rubber Legs#4-10
Rogue Foam Stone#4-10
Stimulator#6-14

Angler Notes

Why it matters: Few aquatic insects move fish like salmonflies. Their size gives trout a big-calorie target, and the pre-hatch nymph migration plus the adult fall-in phase both concentrate feeding along banks and current seams.
Imitation tips: Fish large, dark stonefly nymphs with a sturdy profile before and during the hatch. For adults, use buoyant orange-and-dark salmonfly patterns that suggest the oversized body and tented wings; an egg-laying female look can be useful when adults are active over the water.
Key life stages: NymphAdult
Presentation: Probe banks, soft edges, seams, and the shallows beside fast water with nymphs, since mature insects migrate shoreward before emergence. During the adult phase, work tight to banks, grassy edges, rocks, and overhanging structure with deliberate drifts, occasional twitches, or a skated egg-layer presentation when fish are looking up.

Identification

Key features: Nymphs are thick-bodied, very large stoneflies with a dark back, lighter belly, and a robust crawling profile. Adults are oversized orange-and-dark stoneflies with long wings held flat over the body; females may show a bright orange egg mass at the tip of the abdomen.
Size: Nymphs commonly run very large and can exceed 2 inches; adults are likewise among the largest stoneflies anglers see.
Coloration: Nymphs are dark brown to nearly black above with a paler underside and sometimes subtle abdominal patterning. Adults are dark overall with bright orange on the abdomen, leg joints, and parts of the thorax.
Similar bugs: Golden StoneSkwala StoneYellow SallyLarge dark stonefly nymphs

Habitat

Water types: Freestone riversFast runsRifflesPocketwater
Substrate: Medium to large loose rock and rubble in higher-gradient channels, with mature nymphs shifting toward shallow bankside rocks before emergence.
Conditions: Clean, well-oxygenated, higher-velocity streams and rivers typical of western salmonfly water.