Insects and other foods the trout may be eating:
1.    Blue-winged Olives (See Below)
2.    Mahogany Duns
3.    Little Yellow Stoneflies - Summer Stones
4.    Slate Drakes
5.    Needle Stoneflies
6.    Little Yellow Quills
7.    Ants
8.    Inchworms
9.    Beetles
10.  Grasshoppers
11.  Hellgrammite
12.  Craneflies
13.  Sculpin, baitfish and small crayfish (Imitate with streamers)

Revised Fly List For The Smokies:
I finally got around to revising the "Perfect Fly" list for Great Smoky Mountains
National Park for the current time of year. It was out of date slightly. The Little
Yellow Quills I just wrote about and the Needle Stoneflies I am currently writing
about will begin to hatch any time, if not already. The weather has become more
favorable for the hatches to begin and for the trout to become a little more active
with the cooling trend we are experiencing.

Needle Stonefly Nymphs:
As with any stonefly, the nymphs are the most important stage of life in respect to
what the trout consume. After all, they are in the water for almost a complete year
versus the adults that are only on the water for a few seconds or minutes at the
most. Of course, the Little Needle Stonefly nymphs stay hidden down under the
rocks most of the time or otherwise, the trout would eat them all.

Just prior to the hatch, they become easy prey for the trout because they must
expose themselves for their wing pads to expand and for their trip to the banks and
large rocks to crawl out of the water to hatch into adults. That's also when imitating
the little nymphs is most effective.

This activity starts taking place in low light conditions. In some of the heavily shaded
streams such as most of the smaller streams in the mid to high elevations, this
occurs much earlier in the day than it normally would. Low light conditions may also
be on heavily overcast days and as early as 4:00 PM later on in the year.
The trout become used to seeing the nymphs and a fly imitating them usually works
fairly well throughout the day, although not as good as it does during the late hours.

You can determine when this activity is taking place fairly easy. If you see an adult
Needle Stonefly the hatch has started. Unless it's later in the season, the hatch is
most likely still continuing. Of course, you could be seeing the last of the adults to
hatch and all of the nymphs could have already crawled out of the water and
hatched. If this activity occurs during the next two to four weeks, most likely the
hatch is underway. If the activity occurs later on in October, the hatch could very
well have ended. Stoneflies live a relatively long time out of the water. There's an
alternative solution. You can imitate the egg laying females and still catch trout late
in the day. We will get to that tomorrow.

The key to fishing any stonefly nymph is to keep it on the bottom. Sure, you may
catch a trout with it drifting as a dropper fly or under an indicator, but I am referring
to how you keep the best odds.
This gets down to the most confusing part of  
any type of fishing.
You can usually catch some fish doing just about anything
that's half way reasonable and
if you are not very careful, doing so can distort
your idea of what works best
. Apply that to this particular situation and it means
you should keep the fly imitating the nymphs on the bottom of the stream where the
real ones are when they crawl to the bank. Doing so will increase your odds of
fooling the trout. Even those of us that fell off of a turnip green truck are probably
smart enough to realize that using a fly that looks like the real nymphs helps a lot.