Insects and other foods the trout should be eating:
1. Blue-winged Olives and Little BWOs
2. Green Sedges (Caddisflies)
3. Cinnamon Caddis (Mostly Abrams Creek)
4. Little Short Horned Sedges
5. Eastern Green Drakes (Abrams Creek)
6. Hendricksons & Red Quills
7. American March Browns
8. Giant Stoneflies
9. Light Cahills
10. Little Yellow Stoneflies (Yellow Sally)
Most available/ Other types of available food:
11. Sculpin, Minnows (Streamers)
KISS A Bug Series - Light Cahills - Part 1
Before I get into the Light Cahill mayflies, I want to point out some things about the insects in
general. It's the common names of the insects that causes all the confusion. So far in
this "Keep It Simple Stupid" series, I have avoided getting into the most confusing of all the
common name groups of aquatic insects - the Blue-winged Olives. Although plenty of them
have hatched since I started the series, I wanted to put off getting into them because when it
comes to the mess common names cause, they are by far the biggest mess of all. Not only are
there many species of swimming mayfly nymphs called BWOs, there are even some crawler
mayfly nymphs called BWOs. Species of insects from several different families of insects are
Next to the BWOs in the most confusing group of common named insects are the Cahills.
When the "yellow" bugs start hatching in the Smokies, about the only thing most anglers can
recognize is the difference in the yellow stoneflies, the yellow mayflies and the yellow
caddisflies. Some can't even do that as simple as it is to do that. I call it the "Yellow Bug
Confusion" period. I just read where a guide, and a guide that is recognized as someone who
knows the local insects well, referred to PMDs in the Smokies. In fact, I have seen this appear
on various blogs several times by several different anglers. A Pale Morning Dun is strictly a
western mayfly. They don't exist in the Eastern United States. Here again, PMD is a common
name and a common name can be anything anyone wants it to be. In this particular case,
using the name Pale Morning Dun for an eastern mayfly is so far off base you may as well just
call everything a bug. It just muddies up the water to the point it's completely useless to call
any insect by any name.
Thanks to the warm Winter we had, the little Light Cahill mayflies have already started to hatch
in a few areas of the Smokies. In most areas of the East and Mid-west where these mayflies
exist, they don't hatch until Summer. Normally they don't start hatching in the Smokies until
about the first of May, but I spotted a few last week.
Learning the insects that exist in the streams of the Smokies isn't really a difficult
task at all. In fact, with a little effort, any twelve year old student should be able to learn most
all of the things you need to know about them all in a short time. Only two things are required.
One is a willingness to learn to identify them and to learn the differences in their behavior
and habitat. The second thing is to avoid the common names that causes all the
confusion. Of course, that leaves you with the crazy Latin names of the bugs but you don't
have to be able to pronounce them or even remember them as such. You just have to be able
to recognize the differences in them. Call them bug 1, 2, 3, 4, if you like.
Part of the reason the Light Cahill mayflies are easily confused, even by those that know their
bugs quite well, is the fact the scientist were the first to confuse them. That occurred
when only visual methods were used for identification. DNA corrected many of those errors but
it also created more confusion.
The Light Cahills are species that belong to the Heptageniidae family of mayflies. This family
includes the most plentiful mayflies in the streams of the Smokies. In the same family
with the Cahills are the March Browns and Quill Gordons. The reason they are common in the
Smokies is because they are clinger mayfly nymphs. They prefer fast water streams.
Now, to refresh the KISS memory, "genus" is just a group of different species of insects in a
family that are similar to each other. The Light Cahill belongs to the Stenacron genus. As far
as trout anglers are concerned, this small genus includes just one important species, the
interpunctatum. A Light Cahill is a Stenacron interpunctatum. One thing that makes them
important in the Smokies is the fact they hatch in all the streams and over a long period of time.
Now so far, this seems simple unless you happen to know something about bugs. If you don't,
skip this part and avoid getting confused, but for those that may have not kelp up with the
changes, let me explain.
1. The Stenacron genus is often confused with its sister genus, the similar sounding
Stenonema genus. The Light Cahill mayfly is very similar to some of the Stenonema species
that were changed just a few years ago to Maccaffertium species. That didn't help those that
did know something about these mayflies at all. It accounts for some of the confusion. For
example, the old Stenonema ithaca, which is now the Maccaffertium ithaca, is often called a
Light Cahill. It's also called a Gray Fox, adding even more confusion to the Gray Fox common
2. The Gray Fox mayfly was actually the same as a American March Brown but in the common
name mess, the old Stenonema ithaca also ended up being called a Gray Fox. Because of the
confusion, you will hear Smoky Mountain anglers mention that Light Cahills are hatching all the
way from April until the middle of September.
3. Some of the mayflies they are referring to are not Light Cahills. Some are confused with the
old Stenonema mediopunctatum (now the Maccaffertium mediopunctatum), as well as the
carolina, and modestum species. These mayflies which also exist in the Smokies are
usually and correctly called (if there is such a thing as a correct common name)
4. The Light Cahills are also confused with the Heptagenia group of mayflies or the Little
Yellow Quills that hatch later in the season. That is why you will hear anglers still taking about
Light Cahills late in the Summer and early fall months. These are not even in the same family
as the Light Cahills.
There's another basic reason for all this confusion. The duns of these various species look
much like each other until you look at them closely. The problem with the confusion isn't in the
appearance of the insects - it's with their behavior, different habitats, times and methods of
hatching. It's also in the difference in the appearances of the nymphs, emergers and spinners.
Some of these different stages of their life look very different from each other. Most all of them
Back to the Basics:
Now, I'm sure all of the above scientific names are confusing, especially to those who are just
getting started. I would make this plain and simple if it were not for those guys who would
respond with a lot of corrections in my over-simplification. Some want things simple and some
want them as accurate as a snipper's aim. Scientific names are necessary in order to
designate the insects I'm referring too, or otherwise, I would not use them. If I used common
names only, there would be total confusion. We have that now. For example, if I called a
Maccaffertium Ithaca a "Gray Fox" many anglers would think I was referring to a Maccaffertium
varcium or the old March Brown common name. I could give dozens of such examples.
Common names vary from region to region, book to book and angler to angler. Again, the big
confusion with aquatic insect identification comes from the use of common names.
The Light Cahill mayflies normally hatch from about the last week of April until the end of June,
depending mainly on location, the weather and elevation of the stream. This hatch usually only
last two to three weeks at any one location but the overall duration from the streams from the
lower elevations to the higher elevations can last up to eight weeks. These mayflies can be
found in the tiny brook trout streams as well as the larger watersheds.
As I stated above, it's easy to understand some of the confusion in the common name "Light
Cahill". There's not a great deal of difference in the appearance of some of the Maccaffertium
genus, Stenacron genus and Stenonema genus species. They are all clinger nymphs, the
duns of which look fairly similar. However, there are differences in the behavior of these
various species that warrant attention.
The Heptagenia group of mayflies (often confused as Light Cahills) are also clingers but they
behave quite differently. When we review the "Cream Cahills" you will find that some of those
species are different colors. Some of them are almost white. Some of them have heavily
mottled wings. The sizes of these mayfly species can vary a hook size or two and of course,
the hatch times vary greatly. In the next few articles in this series, i will focus on the real "Light
Cahill", the Stenacron interpunctatum.
Copyright 2012 James Marsh
Quick ID tip:
See the little marks along the front or leading part of the wings? See the three little marks that are
fairly close together in about the middle of the wings from bottom to the top. The three little marks
have a little space around both sides of them. None of the other species of these mayflies have
these same series of three little marks that are separated from all the other marks along the wing.
You can forget about the color, size, and all the other features of the mayfly because this one
thing identifies it from all the others. By the way, this is a male. That's easy to recognize. Mr.
Mayfly - you have big eyes Sir.