08/19/11
Insects and other foods the trout may be eating:
1.    Blue-winged Olives (Little Eastern BWOs)
2.    Mahogany Duns
3.    Little Yellow Quills (
Heptagenia Group)
4.    Little Yellow Stoneflies (Little Summer Stones)
5.    Needle Stoneflies
6.    Slate Drakes
7.    Sculpin, Minnows (Streamers)
8.    Grasshoppers
9.    Ants (includes Flying Ants)
10.  Beetles
11.  Craneflies

The Little Known But Plentiful Mayfly - Little Yellow Quill
When we first started studying aquatic insects and finally got a permit to catch and
take pictures of the insects in Great Smoky Mountains National Park, we were able to
determine the family, genus and species of the little yellow mayflies we were seeing
almost daily from as early as the first of September to as late as end of November.
They are part of what's called the Heptagenia Group of mayflies, which consist of
different genera from the Heptageniidae.

To be specific, there are normally three genera including in the Heptagenia Group.
They are the
Heptagenia, Nixe and Leucrocuta genera. We collected, photographed
and macro video taped the nymphs, duns and spinners. We knew they were clingers
and we also knew they were not Light or Cream Cahills. We discovered they were
species from the
Heptagenia and Leucrocuta genera. Discover Life list them as
Heptagenia julia, Heptagenia marginalis and Leucrocuta thetis species. We have
confirmed that all three species exist. These mayflies hatch at slightly different times
but all of them in the Fall season.

The mayflies are not rare. They are very plentiful. What's amazing is there are some
rather large hatches that take place. They occur just about in all the streams that
have fast water but mostly the mid to higher elevations. What's even more important is
that they hatch at a time of the year when few other insects hatch, yet they are almost
unknown. To put it very bluntly, it shows just how little is known about the trout food in
the streams of the Smokies and the entire Southeastern United States for that matter.
As I have mentioned before, not one singe book has ever been written on the aquatic
insects of the Smokies or the Southeast, yet there are hundreds of books on other
sections of the country. There's even books that have been written on the aquatic
insects of some individual streams.

Some will try to tell you the insects are less important in the streams of the Smokies
than elsewhere but guess who it always is that contents that? The same ones that
don't know a mayfly spinner from a June bug. There isn't anyway anglers fishing in the
Fall season havn't noticed them. I think they must be confused with Light Cahills. At
the same time, I can name several other very plentiful species of aquatic insects that
fit the same "little known" category. I just wrote about the Mahogany Duns and the
Little Needlefly stoneflies, to name two of many other aquatic insects that are plentiful
but not well known..

These mayflies, along with several other aquatic insects that we discovered in good
quantities, convinced us that other than what Discover Life has found and listed as
existing in the park, there's very little known. The entomologist involved in Discover
Life are obviously not fly anglers. If there is other information, someone is keeping it a
secret. It hasn't been  published, not even on the web.

The clinger nymphs of these mayflies are even common in the smaller brook trout
streams in the higher elevations. They do well even in water with a very low pH. You
can find the duns and spinners in very plentiful quantities at times. If you consider the
number of them on the water on a square yard of bottom basis, they would compare
to the Quill Gordons or other larger, early season hatches in the Smokies. They also
occur in the lower elevation streams but they don't seem to be quite as plentiful as
they are in the streams at the mid to high elevations.

The "Little Yellow Quill" is the common name given to several species of the

Leucrocuta
genus of mayflies that are fairly common in many Eastern streams. One
thing for sure is that the name "Little Yellow Quill" certainly fits the ones in the park.
By the way, they shouldn't be confused with the Western "Yellow Quill" or
Epeorus Albertae.

I will write more about them tomorrow, starting with the nymphs.
































Copyright 2011 James Marsh