I was first introduced to this pattern while trout fishing in one of my favorite areas in the United States, the southern Appalachians.  Although I hail from the northeast, I have family in the south and spend a lot of time fishing in mountains of western North Carolina and Tennessee.  I am always intrigued by local fly patterns and my search for authentic southern Appalachian trout flies soon uncovered a strange looking nymph called a Yallar Hammar.  This fly, like many Southern Appalachian patterns, really stood out from the traditional nymphs in my fly box.  Possibly tied to imitate a golden stonefly this simple palmered nymph proved to be a very effective pattern.  The fly is easy to tie but finding the materials turned out to be the biggest challenge.  In its original form, the fly was tied with the primary wing feathers of the yellow-shafted flicker which happens to be a protected species.  The yellow-shafted flicker also goes by the name of a Yellow Hammer or Yallar Hammar if pronounced like the locals do. Since the namesake feathers are hard to come by, substitutions have to be made.  Yellow dyed wing feathers of doves or bobwhite quail make a fair substitute, but they can be hard to come across unless you harvest and dye materials yourself.  My meager supply of feathers for this pattern came from a flicker that had been killed by a neighbor's cat and some dyed morning dove feathers.

At one point a reject from my tying bench ended up in my bluegill box.  The fly proved to be a real killer, so I now tie and fish them more for panfish than trout.  I tie them on a 3x long nymph hook with a few wraps of lead wire as an underbody.  I find a little bit of extra weight crucial for this pattern.  Without the lead wire, the fly will not break the surface tension of the water and will float like a cork.  You don't want the fly to sink like a stone so go light on the weight.  I also changed up the body color.  The original version calls for a black wool body; I brightened up the fly by using a yellow wool body instead.  

My preferred presentation with this pattern is to retrieve it slowly over the tops of submerged weed beds and along the edges of lily pads.  I love watching fish crash up through the weeds or out of cover to smash this fly!  

The recipe for the original version goes something like this:

Hook: 3x long nymph hook of choice
Thread: Black 70 denier
Underbody: A few wraps of .010 - .020 lead wire
Tail: Gold Pheasant or yellow grizzly hackle fibers
Body: Black floss or wool (to tie my version substitute yellow wool or floss)
Hackle: Imitation Yellow Flicker feather palmered through body