If you opened up the fly box of a new fly fisher and the fly box of a seasoned veteran guide, you would find the Pheasant Tail Nymph in there somewhere. Most likely, the newbie would have 1 or 2 Pheasant Tails stashed away somewhere in the box. The guide may have rows upon rows of various sizes and colors of the nymph. The reason is simple. They work and they work well. My favorite PT nymph is a # 16 bead head, flash back, pheasant tail nymph (BHFBPT). I have been tying some olive colored ones in size 18 on a straight eye hook that have proven themselves. The PT nymph can cover pretty much anything you want it to be. If you tie one on, you are giving yourself a good chance to cover small stoneflies, caddis, mayflies and midges. There aren’t too many patterns that can do that. Tying them is pretty straight forward and there are as many ways to tie them as there are variations to tie them up. I have been using 1 piece of pheasant tail for the entire body since I first heard about it way back when. I like to tie mine with a tapered body, so I build up a body with thread to make the taper. I like to use a flat thread such as UTC 70 or more specifically, MFC’s new thread in 8/0. I like to use a light brown or brown color to match the body color. Black will work well also. Tie some up in red, olive, natural, black and whatever other color pheasant you can find. The one listed below is an olive #18 tied on a straight eye hook.
Check out Carl Pennington's recent post on Pheasant Tails for more info and variations.