The Little Yellow Stonefly
Copyright 2014 James Marsh
According to a few books, the Perlodidae family's Isoperla genus includes the bilineata species that is called the Yellow
Sally; however, many other yellow stoneflies are given the same common name. It is just a fact that most small yellow adult
stoneflies are called Yellow Sallies. If a cold water trout stream has fast moving water that stays well oxygenated, chances
are very good, it has some species of stoneflies that in their adult stage of life, are a basic, yellow color. From a food
standpoint, the little stonefly nymphs are far more important than the adults. In most streams where these little stoneflies
exist, they represent a large part of the diet of the trout. They usually exist in large quantities.
There are (9) nine families of stoneflies found in trout streams. Of all the families present, in terms of sheer numbers, the
Perlodidae and Peltoperlidae families usually represent more than any of the other families. Species of the Periodidae
family, the most important one of the two, differ in size, but their basic color and shape is very similar. Species of the
Peltoperlidae family are shorter and more rounded than the Periodidae species; however. all of the species within the family
are very similar in shape and color.
Like all stoneflies (with rare exceptions), the Little Yellow Stoneflies crawl out of the water to hatch. When the nymphs
migrate from their normal locations from under and down between the rocks on the bottom of the stream to crawl out of the
water and hatch, they are very susceptible to being eaten by trout. When there is no hatch taking places, which is about
95% of the time, stoneflies are basically safe from the trout. While it may not be rare for a stonefly in its very early stages of
development to become dislodged and subject to being eaten by a trout, they don't regularly show up in drift samples. It
has been our experience that behavioral drifts, which usually occur under low light conditions, or during the night, don't
contain substantial numbers of stonefly nymphs. The great majority of stonefly nymphs are eaten during a hatch.
In some trout streams, it isn't unusual to find several different species of stoneflies, including the Little Yellow species. In
these streams, there is usually a hatch occurring more often than one would may think. In those cases, the bottom line is
that your odds of success are fairly good if your are fishing an imitation of a Little Yellow stonefly nymph most any time of
the late spring, summer, and early autumn seasons. There's another advantage provided by a Little Yellow Stonefly hatch.
They often deposit their eggs during the daytime. Many other stonefly species deposit their eggs during the evening hours.
All of the species of these two families of stoneflies live in fast water. They must have fast flowing, clean water to survive.
Prior to the hatch, the Little Yellow Stoneflies will move along the bottom of their fast water habitat to the banks where they
will crawl out of the water and hatch. Some of them crawl up on stones and rocks that protrude out of the water to hatch, but
the majority use the banks. Just as soon as they get out of water, they begin to shed their shucks and in a very short time,
they are able to fly away. The best chance the trout have to eat them is prior to the hatch, during their migration to the
banks. The trout can easily see what is taking place and will actually intercept them as they attempt to reach the banks of a
These different species of Little Yellow Stoneflies hatch at different times of the year, depending on the particular species.
Most of the Yellow Sallies, or species of the isoperia genus, hatch during the Summer. If it is a cloudy, overcast day, the
nymphs will crawl to the banks in the late afternoon. The later in the day, the better the fishing usually is. If a hatch is in
progress, you can usually take trout imitating the migrating nymphs anytime during the late afternoon.
Imitating the Nymph:
If you walk up to the bank and cast, or if you walk up to the bank and proceed to wade out into the water, you are usually
going to spook the very trout you are trying to catch. Where the trees and bushes allow, you should first cast from a short
distance away from the banks. You should keep the nymph on the bottom all the way back to the bank. Keep in mind, the
trout don't necessarily have to see you to spook. If you are not careful, they can actually hear you walking on the bank
close to the water. They are able to detect the sound through their lateral line.
If you have to wade to cover the banks, ease up to the stream as quietly as possible. When you do get in the water, wade
away from the bank ten to twenty feet, and fish the nymph down and across, allowing the nymph to swing all the way back to
the bank in the current. In most cases, this method works better than presenting the nymph using an up-stream cast.
As you cover the water a long the bank, continue to move downstream a foot or two each cast, covering all of water along
the bank. If you cast out a few feet using a reach cast that ends with your rod pointing towards mid-stream, you can slowly
swing the rod back in the opposite direction, ending up with it pointing toward the bank. This will swing the fly from
several feet out in the stream, all the way to the bank. Using this method, you can cover approximately twenty to thirty feet
of water on each cast. Of course, this is to just give you a general idea as to how to fish the nymph. You will have to make
changes depending on the particular stream and stream composition. For example, if there is a run near the bank, you may
only need to swing the fly a few feet to cover the water where the trout are likely feeding on the migrating stonefly nymphs.
If your fishing small streams, you will likely need to make longer cast than you are probably use to making. You need to
keep the fly at least twenty feet away from you, depending on the water depth and current. In shallow water, you may need
to keep the fly as much as thirty feet from you to keep from spooking the trout. Remember, when you are making
downstream presentations, the trout will be facing you.
Make sure you keep the fly on the bottom. If it is swinging up off the bottom, mid-depth, or near the surface, you are not
going to catch many fish. Weight it down, and keep it right on the bottom. When you pick the fly up slightly off the bottom,
it will usually swing toward the bank a few inches. Let the fly get back down on the bottom before you lift the rod to swing the
Imitating the Adult:
The different species of the Little Yellow Stoneflies deposit their eggs at different times of the day depending the time of
year they hatch. Some species only deposit their eggs during the evenings. Most of the Summer Stoneflies (Peltoperlidae
family) deposit their eggs during the evenings. The isoperia species, or Yellow Sallies, usually start depositing their eggs in
the afternoon prior to dark. If it is very cloudy, or overcast, egg laying can take place a few hours before dark. This is a very
important aspect of the Yellow Sally egg laying event. You can catch trout on the surface feeding on the egg laying
stoneflies for up to an hour or two during many late afternoons. The "catching" is usually best just before dark but the
overall duration usually last long enough for one to catch at least a few trout.
You should actually observe stoneflies depositing their eggs before you spend a lot of time imitating the egg laying process.
They are large enough that you can easily see them dropping down to the surface, usually bouncing along on the
surface, dropping their eggs. Sometimes they will lite on the surface for a short time but for the most part, they knock their
eggs off by touching the surface. They will usually deposit their eggs in the riffles and runs. Wherever you see them
depositing their eggs is where you should present imitations of the adult. If egg laying is going to occur, you should be able
to find the adults during the day, resting along the banks in the bushes or grass.
It would be nice if you could imitate the actual bouncing type of action, but I can't make my imitation do that without spooking
the trout. You can jerk the fly around some, but I end up spooking more trout than I fool. I think it is best to use a drag free
drift. Up and across presentations work best for this.
June 2014 Issue
don't care where you fish for trout, eastern, mid-western or western states, most likely your going to find Little Yellow
Stoneflies present. Of course, most of the time they will exist as a nymph, not as an adult fly. One reason for their
abundance is there are several species of adult stoneflies that are various shades of yellow. Anglers tend to call all of
them Yellow Sallies. You cannot say that is either right or wrong, because common names are just that - common names.
Perfect Fly Little Yellow Stonefly Adult (Yellow Sally)