I wrote an article for "Fly Tying" a magazine published by Frank Amato before it became the current "Fly Fishing & Tying Journal". It was about creating extended-body mayfly patterns by chain-stitching thread. Les Johnson, then editor of the magazine told me that it was very well received by the readership. I have continued to tie and fish this style of mayfly for Blue-winged Olives, Pale Morning Duns, Callibaetis, Flavs and Mahogany Duns. It can be tied to imitate almost any mayfly type. On smoother waters, with selective feeding fish, it has performed great. I have even used it as a cripple or emerger pattern by tucking the extended-body down around the bend of the hook.
The chain-stitching technique can be done by hand and is explained in my little book "Creative Flies" published by Amato, who recently, let it go out of print. It is now only available through on-line book dealers.
I love to fish this pattern to trout sipping adults off the surface. It is best to use a hook one size smaller than the natural. The extended-body makes a size eighteen into a size sixteen. I also try to find tying thread that is not too waxy. This helps when stitching the body and dividing the tail fibers.
The Blue-winged Olives are hatching now. I think I'll tie a handful up and go fishing!