Fly of the Month:
Split-Foam-Back Baetis

This month’s fly is an original created by some of the guides who regularly work the Gray Reef section of the North Platte River up in Wyoming, including Bob Dye out of the Blue Quill Angler. Bob says it was a group effort, but its economical shape looks nothing like the work of a committee.

The main thing is that Bob swears this baetis fly works on the big fish up there and that he has found it also works really well on the rivers around here – the South Platte and the Roaring Fork to name a couple.

Hook: TMC 2487 (The one shown here is a #20; think small.) Thread: Tan or Gray 8/0 Body and legs: Tan mallard flank fibers. Substitute other colors if you don’t have tan. Rib: Gold Wire, x-fine (Lagartun brand is the thinnest) Wing case: Black Foam – 2 mm wide x 1 mm thick strip Split back: Pearl Flash, small size

Tying Instructions

Remember that one of the goals is to keep this fly really thin, so try not to waste any extra turns of thread as you tie. Also, keep your wraps really smooth. Start by tying on your thread mid-hook and working your way back to and down a little onto the bend of the hook. Bob says that on most baetis imitations he doesn’t go onto the bend of the hook, but this one is different.

Next, select a cluster of fibers from a mallard flank feather, probably 12 to 20 fibers, depending on the size of the hook. Straighten the fibers so the tips are even and then tie in so that the tips extend beyond the end of hook just enough so that if you bend them down, they are flush with the bottom of the hook. Do not clip the butt ends. Leave them hanging over the eye for now. You will use them later for the body and the legs.


Tie in the gold wire at the back where you have tied in the mallard fibers. Be careful to use very few wraps and very even wraps. You will trap the mallard feathers along the top of the hook as well as you move the thread forward to the point of the hook, but no farther.

Now take the gold wire and wrap it forward with wraps roughly 1/16th of an inch apart. Tie off where your thread was stopped earlier. Again, be careful to use no unnecessary wraps. Keep it thin.


At this point, tie in the pearl flash right on top so that it is just about in the middle of the hook. Leave it hanging there, pointing over the bend of the hook. Wrap your thread up to the eye of the hook, capturing the mallard feathers in the process and leaving the rest of the feathers hanging out over the eye of the hook.

Tie in the thin piece of black foam in front of the pearl flash, with the thinner edge lying along the top of the hook and the thicker part up. First make a couple of wraps at the tip of the foam strip just behind the eye of the hook and a couple more just behind the pearl flash. A longer piece of the foam will hang back toward the bend of the hook. When you tie down the foam this way, that will cause the foam to pop up in sort of bulb between the pearl flash and the eye of the hook. Take some shape scissors and trim off the top of that bulb. Then use a few wraps of thread over the trimmed piece to create the thorax.


Now pull the trailing piece of foam forward over the thorax and tie it down behind the eye of the hook with a couple of wraps. Next, pull the pearl flash forward over the foam and tie down, making sure it is pulled snuggly before tying off. This is the same thing you do when tying a flashback pheasant tail.

All that remains is to deal with the mallard feathers that still hang out over the front of your hook. Divide those in half. Pull back the half on the far side so those now are pointing back along the side of the hook toward the bend and tie down with a couple of wraps behind the eye of the hook. Do the same with the other half, except along the near side of the fly. This time use three tight wraps and tie off.


Whip finish. Trim the legs to about 1/8th of an inch or so. Finally, put a drop of cement on the fly to secure it really well. Enjoy! - John Haile