Even though the pattern calls for z-lon, I've substitued plastic canvas yarn, which I like almost as well, and is very inexpensive.

First, tie in a sparce trailing shuck of amber z-lon about as long as the body of the fly.

Next, dub the body forward 2/3 of the way to the eye. You want the dubbing to be a little loose to give a fuzzy appearance.

Next, double over a piece of white or gray z-lon and tie it in to make the loop wing. You want the wing to ride low over the back of the body.

Fianlly, make a head of tan dubbing. You also want this to be loose for a fuzzy look.

This pattern is from Craig Mathews' book "Western Fly Fishing Strategies". It is one of a number of patterns is that book that ride low to the water, and have a very fuzzy appearance. I like the fuzziness of the pattern as it gives the fly the illusion of movement on the water. This fly is meant to be fished dry.

I'm a little confused on the name as it's listed as "Irise" in the book and "Iris" on the VFS. No matter, it still fishes great.