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© 2026 Barbless.co. Flow and gauge data from USGS; weather from Open-Meteo. · v2026.10.18.2

  1. Home
  2. Hatches & Forage
  3. Caddisflies
  4. Grannom Caddis

Updated July 15, 2026

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Grannom Caddis

Hatches › Caddisfly

Caddisfly

Grannom Caddis

Brachycentrus · genus

A classic spring caddis group whose larvae, pupae, and fluttering adults can pull trout to feed hard.

Overview

Category

Caddisfly

Category

Caddisfly

Category

The insect or forage category for this profile.

Size

Mostly small to medium; commonly imitated around hook sizes 12-18 depending on stage and water.

Size

Mostly small to medium; commonly imitated around hook sizes 12-18 depending on stage and water.

Size

Typical size range anglers imitate on the water.

Key stages

Eggs, Free Living Larva, Cased Caddis, Pupa, Emerging Adult, Adult Caddis, Egg Laying Adult

Key stages

Eggs, Free Living Larva, Cased Caddis, Pupa, Emerging Adult, Adult Caddis, Egg Laying Adult

Key stages

Life stages most relevant to fly fishing this hatch or forage.

Water types

rivers, streams, riffles, runs

Water types

rivers, streams, riffles, runs

Water types

Water types where this bug or forage is commonly found.

About Grannom Caddis

Brachycentrus is a genus of humpless casemaker caddisflies in the family Brachycentridae, commonly called grannom caddisflies. For anglers, this group matters because fish may key on them in all three fishable stages: larva, pupa, and adult; it is also widely known as Mother's Day Caddis.

Also known as: Mother's Day Caddis

Life Cycle

The Caddisfly undergoes a complete metamorphosis, starting as eggs in the water and progressing through larval and pupal stages before emerging as an adult. Adults mate, lay eggs, and then the cycle begins again.
Eggs

Eggs

Female caddisflies deposit clusters of eggs in or near the water, marking the start of their life cycle.

Free Living Larva

Free Living Larva

After hatching, these larvae feed and grow underwater, typically found along the stream bottom. They are an important food source for fish.

Cased Caddis

Cased Caddis

Many caddisfly species construct protective, portable cases from natural materials like sand, pebbles, or plant matter. They inhabit these cases underwater as they grow.

Pupa

Pupa

During spring, the caddisfly enters the pupa stage in sheltered spots, often beneath rocks in flowing water. This is a transformative phase before emerging as an adult.

Emerging Adult

Emerging Adult

The adult caddisfly rises to the water's surface, breaking free from its pupal skin to begin its aerial life. This stage is highly attractive to actively feeding fish.

Adult Caddis

Adult Caddis

Adult caddisflies fly, mate, and remain close to streams and rivers. Their adult lifespan is relatively short, focusing primarily on reproduction.

Egg Laying Adult

Egg Laying Adult

After mating, female caddisflies return to the water to deposit their eggs, completing the life cycle and initiating the next generation.

Stages
Anglers mainly fish the larva, pupa, and adult. Larvae live in portable cases, pupae become active before emergence, and adults ride or skitter on the surface after hatching.
Emergence cues
Most important in spring; watch for warming water, mild afternoons, and visible adult activity along the surface or streamside cover.
Behavior
Larvae stay near the bottom in their cases. Pupae rise and drift during emergence, often triggering the most decisive feeding. Adults may flutter, skate, or collect in eddies, and spent insects can drift back low in the film.

How to Tie Grannom Caddis Patterns

Eggs

Eggstasy Egg #flytying #flyfishing #flyfishingtactics

The Unknown Angler

Materials

  • Hook10Orvis 1P2A - black nickel
  • Slotted Tungsten Bead13CF3 2340 - Copper 5/32
  • Eggstacy Dubbing2. FL Cheese
  • ThreadWhite

Free Living Larva

Caddis Larva

tightlinevideo

Materials

  • Barbless Tactical Czech Nymph Hooksizes 14-16
  • UTC 70 Denier or 8/0yellow olive
  • Australian-possum dubbinglight olive
  • Australian-possum dubbingdark brown

Cased Caddis

Cased Caddis Jig | Maybe The EASIEST Fly You'll Tie in 2025! | Fly Tying Tutorial

Fly Fish Food

Materials

  • Eco Warrior dubblack
  • pepper box dubbingEco Warrior dub or Ultra dry dub
  • dubbingRusty orange
  • dubbingpolish
  • beadbig old gnarly Wanger of a bead
  • thread

Pupa

Grannom Caddis Pupa

tightlinevideo

Materials

  • Barbless Czech nymph hooksize 16Fulling Mill 5065
  • Thread70 DenierUTC, brown
  • Pheasant tail fibersbrown
  • Round wire.02lead-free
  • Soft wireSmall-sizedolive
  • Rabbit fur dubbingOlive
  • DubbingDave Whitlock's red fox squirrel nymph thorax

Emerging Adult

Tying an Emerger Caddis (Grannom) by Davie McPhail.

Davie McPhail

Materials

  • HookSize 14Light Grub Hook
  • ThreadDark Brown Uni-8/0
  • RibSparton Tackle Clear Wrap Coloured with a Green Pen
  • BodyGrey and Olive Dubbing
  • UnderwingGrey Coq de Leon
  • ThoraxDark Grey or Brown Dubbing
  • PostGrey Para-post
  • HackleCree Cock

Adult Caddis

Grannom Caddis Dry Fly | Best for Caddis Hatches | Fly Tying Tutorial

Trident Fly Fishing

Materials

  • Hook
  • Thread
  • UNI Floss
  • Superfine Dubbing
  • Antron Yarn
  • Deer Hair
  • Head Cement

Egg Laying Adult

Egg-Laying Grannom Caddis

tightlinevideo

Materials

  • Standard dry-fly hooksize 16 - Dai-Riki 305
  • Thread6/0 - olive
  • Crinkled Zelongreen highlander
  • Australian possumnatural gray
  • Straight Zelonwhite
  • Snowshoe rabbit footnatural
  • Hare’s Ear dubbingnatural

Where It Hatches

Grannom Caddis

One species, multiple rivers.

RiverJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC
  • Henrys Fork of the Snake River

Fly Patterns

  • Caddis Pupa#10-18
  • Elk Hair Caddis#12-18

Angler Notes

Why it matters
When trout lock onto grannoms, they often feed by stage rather than by general shape alone. Matching whether fish are taking bottom-drifting larvae, ascending pupae, or adults in the film can matter more than fine color details.
Imitation tips
Carry a simple progression: green or olive larva, dark/olive pupa, and a dark adult with gray-brown wing tone. Slim, sparse patterns usually fish better than overdressed flies, and a touch of sparkle on pupae can help suggest the emerging stage.
Key life stages
larvapupaadult
Presentation
Start subsurface with short-drift larva patterns near the bottom, then switch to emergent pupae on rising fish or during active hatch movement. Fish adults dead-drift first, then add a slight twitch or skate if naturals are fluttering.

Identification

Key features
Look for a small, tent-winged caddis profile as an adult and a case-building larva in the water; grannoms belong to the humpless casemaker caddisfly group.
Size
Mostly small to medium; commonly imitated around hook sizes 12-18 depending on stage and water.
Coloration
Usually dark-bodied adults with gray to brown wings; larvae and pupae are often imitated in olive, green, tan, brown, or dark tones.
Similar bugs
other dark caddismicro caddissedgessmall stoneflies

Habitat

Water types
riversstreamsrifflesruns
Substrate
Rocky to gravelly bottoms with firm structure that supports case-building larvae.
Conditions
Most associated with clean, well-oxygenated moving water.

Eaten By

Brook Trout
Brook Trout
Brown Trout
Brown Trout
Cutbow Trout
Cutbow Trout
Mountain Whitefish
Mountain Whitefish
Rainbow Trout
Rainbow Trout
Yellowstone Cutthroat Trout
Yellowstone Cutthroat Trout

On this page

OverviewLife CycleFly TyingWhere It HatchesFly PatternsAngler NotesIdentificationHabitatEaten By

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  • 1 water
  • 2 fly patterns
  • 6 predator species
  • 7 tying videos
  • 7 life stages

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