Welcome to Fly Tying Tuesday

The Deadly Baetis Imitator That Sinks Fast and Slays Trout in Low-Light Conditions

The Olsen’s Diabaetis Perdigon, designed by competitive angler Devin Olsen, is crafted to closely mimic Baetis nymphs (commonly known as Blue-Winged Olives), which are small, dark mayflies prevalent in many rivers. Its iridescent purple or violet body, created using perdigon-specific tinsel, replicates the subtle blue-purple hues of natural Baetis nymphs, especially effective during winter or low-light days when these insects are active. The slim, streamlined profile reduces water resistance for quick sinking, emulating the natural drifting behavior of dislodged Baetis in the current. The addition of a wire rib enhances durability and adds a segmented look that matches the insect’s body, while a subtle flash from the tinsel sets it apart in murky water, making it “diabetically” sweet to selective trout feeding on these nymphs.

Let’s Tie, see Kyle in action in the video!

Materials Used:

Hook: Fulling Mill Jig Force Straight Point Black Nickel Barbless Hook – Size 16

Bead: MFC Slotted Tungsten Beads – Mottled Matte Grey

Thread: Danville 6/0 Flymaster Waxed Thread – Black

Hot Spot Thread: UTC Ultra Thread – Fluorescent Fire Orange 70d

Tail: Hareline Coq De Leon Feathers – Light Speckled Brown

Rib: UTC Ultra Wire – Silver sm

Body: Semperfli Perdigon Body – Iridescent Pearl

Coating: Solarez Fly Tie Formula Thin Hard

Step-by-Step Tying Instructions:

Step 1: Prepare the Hook and Bead: Slide the slotted tungsten bead (silver or copper) onto the hook, with the small hole facing the hook eye. Place the hook in your vise, bead forward.

Step 2: Start the Thread Base: Attach the black thread behind the bead and wrap a smooth thread base down to the hook bend and back up to just behind the bead. This creates a foundation for the materials.

Step 3: Tie in the Tail: Select 3-4 Coq de Leon fibers (about shank length). Tie them in at the hook bend, extending rearward. Trim the butts and secure with thread wraps.

Step 4: Tie in the Rib Wire: At the same tie-in point, secure the tag end of the small silver wire rib. Wrap the thread forward over the wire butts to behind the bead, keeping everything smooth.

Step 5: Tie in the Body Tinsel: Secure the perdigon tinsel (iridescent purple) at the hook bend, on top of the tail tie-in point. Wrap the thread forward to behind the bead, covering the tinsel butts.

Step 6: Wrap the Body: Advance the tinsel forward in tight, overlapping turns to form the tapered body, stopping just behind the bead. Tie off the tinsel and trim the excess.

Step 7: Counter-Rib the Wire: Wrap the silver wire forward in open spirals (4-6 turns) over the tinsel body for segmentation and reinforcement. Tie off behind the bead and trim the excess (helicopter the wire to break it cleanly).

Step 8: Build the Hot Spot: Switch to fluorescent orange thread. Wrap a small collar (2-3 turns) just behind the bead to create a bright hot spot. Tie off and trim.

Step 9: Form the Wing Case: Apply a small drop of black UV resin or nail polish over the thread hot spot and thorax area to simulate a wing case. Shape it smoothly with a bodkin if needed.

Step 10: Coat the Body: Apply a thin layer of clear UV resin over the entire body and rib, avoiding the tail and bead. Use a bodkin to spread evenly for a glossy, streamlined finish.

Step 11: Cure and Finish: Cure the resin with a UV light until hard (about 10-20 seconds). Add a second thin coat if needed for extra shine and durability. Whip finish with black thread behind the bead, trim, and apply a tiny drop of head cement if desired.

This tie takes about 5-10 minutes once practiced and results in a durable, fast-sinking nymph. Variations in the video may include slight color tweaks (e.g., dark violet vs. copper), but the process is consistent.

How to Fish It

This perdigon-style nymph excels in tight-line Euro-nymphing techniques but can also be used under an indicator or as part of a tandem rig. Rig it as the point (bottom) fly with a heavier tungsten bead to reach deep runs, pools, and riffles quickly—its slim design cuts through currents without drag, allowing a natural dead drift. Focus on colder months (winter through early spring) or anytime Baetis hatches are occurring, particularly in tailwaters or freestone rivers with slight water color. Present it with minimal movement, letting the current do the work, or add occasional subtle twitches to imitate an escaping nymph. It’s deadly on picky trout in pressured waters, often outfishing more traditional patterns due to its fast sink rate and flash. Pair it with a lighter dropper fly like a midge or caddis pupa for versatility.

---

Check out some of our favorite Fly Tying Gear:

• Vise – Dynaking Barracuda Deluxe Pedestal Vise
• Scissors – Kopter ABSOLUTE Blade Micro Serrated Edge Thin Point
• Bodkin – Dr. Slick Jumbo Carbon Fiber Bodkin
• Whip Finisher – Tiemco Midge Whip Finisher
• Tool Kit – Umpqua Dream Stream Plus 7 Piece Fly Tying Tool Kit