Mop Fly

A wildly effective attractor pattern that pushes the boundaries of traditional fly design. Built from microfiber chenille, the Mop Fly mimics cased caddis or grubs and excels in off-color water or high flows. Its oversized body and quick sink rate make it a staple in any Euro nymph box.

Mop Fly fly pattern - imitates Caddis Larvae, Grubs tied for Trout
  • Beginner
  • Year Round
  • Trout
  • Size 10–12

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A wildly effective attractor pattern that pushes the boundaries of traditional fly design. Built from microfiber chenille, the Mop Fly mimics cased caddis or grubs and excels in off-color water or high flows. Its oversized body and quick sink rate make it a staple in any Euro nymph box.

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Materials

Hook
Hanak H 400 BL Jig Hook, sizes #10-#12
Thread
UTC Ultrathread 140 Denier - Brown
Bead
Hareline Slotted Tungsten Beads - Black - 5/32" (3.8mm)
Tail/Body
Mop Bodies - Cream
Collar
SLF Spikey Squirrel Dubbing - Natural Gray

Overview

A high-sink-rate nymph pattern tied with a chenille or microfiber “mop” body, often in chartreuse, tan, or pink. Finished with a tungsten bead and optional hot-spot collar or dubbed thorax. Incredibly simple and fast to tie — just lash the mop to the hook, add a bead and flash if desired. Effective as an anchor fly in Euro rigs or high water conditions.

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Behavior & presentation

Natural Behavior
Free-living caddis larvae crawl along substrate but tumble and drift when dislodged by high water, their soft segmented cream or chartreuse bodies becoming vulnerable prey. Bright coloration stands out against rocky bottoms during turbid conditions, triggering opportunistic feeding responses as these grub-like larvae lack the protective cases of their cased caddis cousins.
Where Trout Eat It
Runs, pockets, and fast riffles in both rivers and lakes, particularly in turbid water.
How to Fish It
Dead drift near bottom with tight-line Euro techniques or high-stick nymphing to maintain contact.
Best Water
Target pockets, drop-offs, and seams during high water or off-color conditions.
Strike Type
Dead drifting near bottom with tight-line Euro techniques or high-stick nymphing, watch for sag in the sighter or pauses in line movement. Trout grab this pattern aggressively in turbid water — strikes register as sharp ticks or sudden weight on the rod.

Fishing strategy

Rigging Suggestions
Use 4X-5X tippet. Excellent as a point fly in Euro nymph setups with 2.5-3.5mm tungsten bead. Also effective 18-24 inches below a buoyant dry fly or indicator for deeper drifts.
Seasonal Timing
Year-round producer with exceptional results during runoff (April-June) and after rainstorms when water is high and turbid. Remains effective through in tailwaters.
Pro Tips
The dense chenille and tungsten bead sink fast, getting the fly into the strike zone quickly. Match body color to local caddis larvae—tan, olive, chartreuse, or cream.
From River & Run

Where to fish it

Rivers anglers pair with this fly, with local shops that stock it.

Open River & Run

River details and fly shops from River & Run, our sister site.

Entomology

Free-living caddis larvae crawl along the bottom substrate, tumbling and drifting in the current when dislodged from rocks during behavioral drift or high water events. These soft-bodied larvae lack the protective cases of their cased caddis cousins, making them vulnerable and highly nutritious prey items. Their bright coloration (often green, tan, or cream) and segmented, grub-like bodies make them stand out on the river bottom, triggering opportunistic feeding from trout year-round.

Order
Trichoptera
Common name
Caddisfly
Organism
insect
Life stage
larva

Pattern details

  • Stillwater
  • Moving Water
  • Rocky Mountain
  • Southwest
  • Europe
  • tight-line-nymph
  • competition
  • dead-drift
  • caddis-hatch
  • classic
  • guide-fly
  • beginner-friendly
  • attractor
  • searching-pattern
  • high-water

Get this fly

Mop Fly, tied and ready to fish

Hook #10 to #12 · Beginner