Improved Montana Stonefly Top View

The Improved Montana Stonefly is easy to tie.  The goal of this lesson to teach the use of biots for a tail and demonstrate how to make them flare.


  • Hook: 8-12 3xl nymph
  • Weight: lead wire or lead substitute
  • Thread: 8-0 color of choice
  • Tail: Biots
  • Legs: Grizzly Hackle
  • Abdomen: Wool yarn
  • Thorax: Wool yarn
  • Wing Case: Wool Yarn

Place the hook in the vice and wrap lead wire over the center 1/3 of the hook shank.

Hook With Lead Attached

Attach the tying thread in front of the lead and wrap a thread dam in front of and behind the lead wire, forming a tapered body to the bend of the hook.

Place a small amount of black or brown dubbing on the tying thread (use direct dubbing technique) and form a small ball of dubbing at the bend of the hook. This small ball will separate the biot tail fibers.

Dubbing Ball

Select two biots for the tail.  Biots are the fibers from the leading edge of the primary flight feathers of most birds. Attach the biots to each side of the dubbed ball using the soft loop technique. Use a loose wrap.  Once the tails are in position, tighten the wraps as you wind the tying thread toward the tail and the tails will flare.

Biots Attached

Select a piece of wool yarn and attach to the end of the hook at the tail.  Wrap the tying thread to the center of the shank.  Twist the yarn to form a segmented body and wrap forward to mid shank. Tie the yarn off on top of the hook.  Form a loop on the far side and near side of the hook.  These will become the wing case.

Yarn Loops

Pull the remaining yarn out of the way.  Attach a grizzly hackle by the stem end to the midpoint.

Hackle Attached

Wrap the rest of the wool yarn forward to the eye of the hook and tie off. Be sure to leave a lot of space for the head. Wrap the grizzly hackle forward in 2-3 open turns and tie off.

Hackle Wrapped Forward and Trimmed Top and Bottom

Trim the hackle on top and the bottom of the fly. Bring the two loops of yarn forward for the wing case and tie off.

Side View

Form a neat head and whip finish. This is the finished fly.

Improved Montana Stonefly Top View

This is a picture of a Stonefly exoskeleton found on the Middle Fork of the Salmon River in Idaho.

Stonefly Exoskeleton After Hatching

I will be posting a video of tying this fly to youTube soon.