Michigan Flies

Flies / Worm

San Juan Worm

I

A chenille worm for high, off-color water in spring and after fall rains, when earthworms and aquatic worms wash into the drift. The DNR lists worms in brook trout diets but the notes found no Michigan guide naming it; fish it as a heavy point fly with an egg or nymph trailer during March to May runoff, including for steelhead.

#8–14RedPinkWineTanstained water
What the pattern looks like
Reference photos of the San Juan Worm tied by others, shared by their photographers. Not our flies; our own product photos replace these as they are shot.

Photo © Quinn for Fly Deal Flies, used with permission · San Juan Worm Red

Season
Months this pattern is in play across Michigan, derived from what it imitates.
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
Imitates

Forage

  • Aquatic worm
  • Earthworm (washed in after rain)
Fish it for
Brown troutRainbow trout (resident)Brook troutSteelhead

Setups

  • Indicator nymphing
  • Euro / tight-line nymphing
  • Chuck and duck
How it's tied
A
A length of Ultra Chenille lashed to a curved hook: an aquatic worm for high, coloured water, after rain, and any tailwater with silt. Our own write-up of the standard tie, checked against the sources below. Recipe by Charlie Craven, Charlie's Fly Box (2022).

Materials

Hook
TMC 3761 sizes 12-14 (Craven) or TMC 2487 curved 14-18 (Duranglers); sizes 8-12 for bigger worms
Thread
UNI 6/0 to match or contrast the body: red, pink, tan, rust or brown
Body
Standard Ultra Chenille, about 2 in per fly: red, pink, wine or tanMicro Ultra Chenille for size 14 and smaller; Craven likes worm brown with pink thread and dark brown with rust.
Weightoptional
A bead or a few wraps of lead under the thread band
Head cementoptional
Head cement over the thread band

Steps

  1. 1.Start the thread behind the eye and lay a base back to the bend.
  2. 2.Cut a 2 in length of Ultra Chenille and pass each end quickly through a lighter flame, rolling the tip in your fingers while it is warm so it tapers instead of fraying.
  3. 3.Lay the chenille on top of the shank at the bend with roughly two-thirds trailing off the back, and bind it down with four or five tight wraps.
  4. 4.Lift the front of the chenille out of the way and wrap the thread forward to just behind the eye.
  5. 5.Lay the chenille back down on the shank and bind it with a band of tight wraps running from behind the eye back two or three eye-lengths, so the band forms a small oval bump like a worm's saddle.
  6. 6.Whip finish on top of the band, cut the thread, and cement the band.
  7. 7.Check that the rear tag is a little longer than the front one; trim and re-singe if needed. For a fatter worm, wrap the chenille around the shank between the two tie-downs instead of lashing it straight.

From the tier

  • Charlie Craven: do not shy away from bright colours; they work well in off-colour water. He offers red on red, orange on orange, hot pink, and worm brown with a pink thread band.
  • Andy McKinley (Duranglers): it can be tied in about a million sizes, colours and materials, from chenille to chamois to pearl braid, and takes ten minutes to learn; burn the chenille ends so they hold together.
  • Steve Mathewson (2 Guys and a River): drift it under an indicator, and expect it to shine after rain or when a river bumps up and washes worms out of the silt.

San Juan Worm Steps paraphrase Craven's six-step tutorial with Duranglers' singeing tip; the origin summary is from 2 Guys and a River. Unconfirmed: The originator's name is disputed and not given by any fetched source. Also checked against Andy McKinley, Duranglers (2014), Fly Tying: The San Juan Worm and Steve Mathewson, 2 Guys and a River (2017), Know Your Pattern: The San Juan Worm.

Materials to buy
Everything one San Juan Worm takes, each item once: 4 items, plus 2 optional. Quantities are for a single fly. We do not sell components yet; when we do, these will link to them.

Hook and hardware

  • Hooks1 pack of 25

    sizes 10-14 · TMC 3761 or TMC 2487

    Hook

Synthetics, flash and legs

  • Ultra Chenille1 card each

    red, pink, wine, tan; standard

    Body

Thread and finish

  • Thread1 spool each

    red and pink, 6/0 · UNI

    Thread

  • Head cementoptional1 bottle

    Head cement

Other

  • Beads or lead wireoptional1 pack

    Weight

  • Lighter1

    Body

    For singeing the chenille ends.

Sources