OK, This is a fly pattern of mine that goes way back, all be it was a fly l had originated for stillwater fishing it is as deadly fished on moving water systems.

Here is the tying detail. It used my split thread method to form the body. We will shoot some of my tying techniques when l am in CT this April, fact l may tie this fly.

Abdomen is SLF standard, choice of colors may include.
Insect green
Dark olive
Cream
Tan
Orange
Yellow

Body sheath.
Swiss straw, clear or straw.

Hackle.
Ginger to dark brown hen, brown partridge and grouse is also good.
Color to match species.

Thorax and head.
A dark dubbing, l use hares ear most if the time.

Antenna
Two brown mallard shoulder strands.

The body is formed by splitting thread, the only two that work are Danvilles 6/0 FM and Wapsi UTC 7O.
Thread color to match body. Do not use a dark thread for a light colored body.

The body is formed by splitting the thread 505 and inserting the dubbing material into the separated strands, then twisted and wound, what you are aiming to do is to create a body with min amount of material trapped and with a fly away effect, that is why you see the translucence in this fly body.
Regular single strand dubbing techniques will not work as well and neither will teh use of a dubbing loop as you add way extra thread and bulk.

After the body is wound Swiss straw is cut ti a width to surround the body.
The hackles is wound, the head formed and the two antenna tied in rearward.

This fly when fished will pulse with life and mimic the upward motion of a emerging caddis pupa.

Often as l not l will fish 2 or 3 of these at a time, or in conjunction with other wet and soft hackles.

Davy