10/16/08

Fishing the South Holston Tailwater - Blue-winged Olives

The common aquatic insect name "Blue-winged Olive" is about as common a name
as they are in fly fishing. It correctly includes a lot of different mayflies along with
many that don't belong in the category. In our
new mayfly video, we break the
mayflies called BWOs down into four categories - blue-winged Olives, little
blue-winged Olives, eastern blue-winged olives and small blue-winged olives. The
reason we do that is because the mayflies in each of the four different categories
behave quite differently. They all have one basic thing in common. The look alike in
that the duns all have dull, light grayish blue shaded wings and olive tinted bodies.
That is why we only have one basic
"Perfect Fly" for each stage of their life, even
though some are crawlers and some are swimmers. Some hatch below the surface
and some on the surface. Some dive to the bottom to deposit their eggs, some drop
them from the air and others deposit them on the surface. This means that just
having a BWO fly tied on is not enough. You need to know how to determine which
fly - the nymph, emerger, dun or spinner - should be used at any given time and
how and where to present the fly in order to imitate what is happening at the time.

1. What we (and most books) refer to as Blue-winged Olives are baetis mayflies.
There are many species of them but they are all slim, trim, minnow-like nymphs that
dart about. You will find these in most all trout streams including the South Holston.

2. Little blue-winged olives include mayflies of the plauditus, timpanoga,
acentrella and diphetor genus. They do not behave like the baetis species. There
are some of these mayflies in the South Hoston River.

3. Eastern blue-winged olives are drunella species. They are crawler nymphs
with flat bodies and heavy forelegs. They are much wider and stockier built than the
swimming nymphs. The legs extend out from the head all the way back to near the
tail. They crawl and swim very poorly across the bottom from their rocky medium to
fast water habitat to calmer water to emerge. The tails are short. These mayflies
hatch below the surface. I know that these mayflies exist in the headwaters of the
South Holston but I am not certain about the tailwater section. I would assume they
exist there but since I have not specifically verified that, I am not going to discuss
fishing these in forthcoming articles on the South Holston Tailwater.

4. Small blue-winged olives are of the Attenella genus. The attenuata species
are generally called Small Eastern Blue-Winged olives. These mayflies emerge
below the surface, on the bottom or somewhere in between. I am not certain that
they exist in the South Holston. I would assume they do since they exist in the
headwaters of the South Holston River in Virginia.  

Tomorrow I will get into how you should imitate the blue-winged olive mayflies on the
South Holston tailwater.    


Copyright 2008 James Marsh