Insects and other foods the trout may be eating:
1.    Blue-winged Olives
2.    Little Short Horned Sedges
3.    American March Browns
4.    Cinnamon Sedges (Caddisflies) (Abrams Creek)
5.    Green Sedges (Caddisflies)
6.    Little Sister Caddisflies (Abrams Creek)
7.    Eastern Pale Evening Duns
8.    Sulphurs
9.    Little Yellow Stoneflies -Yellow Sallies
10.  Eastern Green Drakes (Abrams Creek)
11.  Giant Stoneflies
12.  Light Cahills
13.  Sculpin, baitfish and small crayfish (Imitate with streamers)
14.  Midges

As mentioned very recently in my articles on the Eastern Pale Evening Dun,
"Sulphur" is a locally used common name given to two closely related mayflies. The
true Sulphur is a
Ephemerella dorothea. It is very much like the Eastern Pale
Evening Dun except it is usually about a hook size smaller and hatches in slower
moving water. It usually hatches slightly later in the year and is another reason the
Sulphur hatch seems to last a long time in some waters. There are other reasons
for the length of the hatch in tailwaters, especially the South Holston River tailwater
in which both of these mayflies exist and hatch over a very long period of time.

Like the Eastern Pale Evening Duns I just finished writing about, the Sulphurs are
not very plentiful in the streams of Great Smoky Mountains National Park. They are
very abundant in the small areas or isolated places they are present in however. In
other words, if you are present and a hatch is occurring, you may wish you had
some imitations of them.

The crawler nymphs inhibit the riffles and runs of the moderate to slow currents.  
This type of water is found in the section of stream that falls on a slow to moderate
decline in elevation as opposed to a steep decent.

The best time to fish imitations of the Sulphur Nymph is just prior to a hatch. The
nymphs become real active and loose a lot of their normal caution. You can fish the
nymph imitation near the bottom using a strike indicator or on the swing. You are
better off fishing a weighted nymph right on the bottom. The fly works best if it's
bouncing along the bottom of the stream.

We use an up and across presentation in most cases. There are some situations
where the water's surface is smooth that you may want to use a down and across
presentation. It is more difficult to get close to the trout in smooth water and the
down and across cast lets you drift the fly by trout that are a good distance from
you. Just prior to the hatch, we much prefer to fish the nymph without a strike
indicator but you can catch fish using one. The choice is a matter of preference.
"Perfect Fly" Sulphur Nymph