A great beginner’s pattern and it will catch fish world wide. Most often considered a Czech Nymph, mine is slightly different in that I don’t include an under-ribbing (see GFF tutorial). It seems to get lost for me, so I stay with the more traditional scud tie of a single ribbing over the shellback.
The hook is a large scud/pupa hook: size 12 (this can be tied large (8) to small (16)). The thread here is 8/0 tan. The ribbing is tied in first at the bend. The ribbing is 4# clear mono. A tan scud shellback is then tied in at the same spot as the wire ribbing. Both the ribbing and shellback are allowed to hang to the rear. The abdomen material is tan rabbit fur, which I twist/dubbed onto the thread. I then wrapped the tan dubbing up the shank 2/3’s of the way. Then I dubbed with a blend of a little peacock Ice Dub and green rabbit fur for the thorax area and made it slightly thicker than the abdomen. Note many Czech Nymphs are usually uniform in thickness rear to front. Then I gently pulled the shellback over the top of the abdomen/thorax out over the hook eye to impart a little stretch (don’t pull too tight and snap the shellback). Tie off the shellback with your off hand and cut off the excess. Make sure the thread wraps are tight enough to secure the shellback. Now wrap the ribbing up the body in equidistant turns and tie it off at the head. Then form a nice thread head and finish.
There are a multitude of color combinations. I did not weight this pattern, but it is normally heavily weighted and fished as a dredging pattern…short line and dredged along setting on any bump. I have posted several earlier posts about Cz Nymphing. Search upper right for all kinds of info…also look at the Vladi Worm for an interesting pattern that will challenge your materials securing skills.