I am not sure of the origins of this fly pattern. I have always associated it with B.C. stillwaters. All that peacock. How could it be forgotten as a general nymph, or perhaps a dragon fly nymph. This is a nice looking nymph, but given the world of fly tying there are always variations. I am posting two versions here..one I am familiar with and then a second one with a hackle collar included. Both could be tied, fished and compared.

Halfback Nymph (Traditional Style)

The above is the B.C. Halfback pattern I have most often seen. This could be tied in various sizes, for various insects and also for streams.

Halfback Nymph (Hackled Version)

This pattern is a variation of the Halfback Nymph. The original nymph has a peacock abdomen with no pheasant tail backstrap over the top. In the hackled version, the abdomen has a hackle fiber tail (not pheasant tail) and a pheasant tail backstrap over the abdomen up to the thorax area. Both have their merits. I am drawn to the original nymph version (top most pattern). The patterns could represent any number of insects.   Excellent Anatomy Info too.