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Brachycentrus
Early April is a quiet time in
West Yellowstone. Vacationing skiers and snowmobilers are gone,
and the summer tourist hordes are still weeks away. The town
belongs to its residents. April is also a time of transition;
winter slowly eases into spring, though ordinary measures of
springtime such as warming days and greening grass fail dismally
as a yardstick in this mountain town. Snow still covers the
ground and will do so for the next month. Most locals are heading
south in search of a warmer climate. Spring has arrived when
you have trouble finding an open restaurant in town, and early
April is that time. For fishermen it is also time to begin thinking
of caddisflies.
Heavy emergences of Brachycentrus
occidentalis (Brack-ee-sen'-trus ox-uh-den-tay'-lis) begin
around the tenth of April on the thermally influenced waters
of the Madison and Firehole Rivers in Yellowstone Park. This
is the first major caddisfly of the
year to emerge on trout streams, and it is fed upon readily
by the trout. It is a caddis that exhibits considerable sexual
dimorphism in size: the females are a full size #14, the males
a #16. Both are a choice meal for fish whose main surface foods
until now have been small Baetis mayflies and midges.
Brachycentrus are dark gray in color, almost black at
times, and both sexes have distinct olive-hued stripes on the
sides of their gray abdomens. These stripes, combined with the
time of year they emerge, is a reliable identification feature.
The emergences of B.
occidentalis on the Madison and Firehole are unique because
of the thermal influences in the watershed. Brachycentrus
is normally an explosive, concentrated emerger, with millions
upon millions of individuals emerging over a period of a few
days. Instead of these typically quick, mind-boggling emergences,
the Park waters experience less intense hatches extended over
a much longer period. Fishable numbers can be seen on both rivers
from early April until the beginning of July. Yellowstone Park
doesn't even open for fishing until Memorial Day weekend, but
fishermen can still have a month of Brachycentrus activity.
Brachycentrus occidentalis
is also referred to as the "Mother's Day caddis",
especially in the Livingston and Bozeman areas, where the nearby
Yellowstone and Madison Rivers experience incredibly heavy emergences
around, coincidentally enough, the holiday of the same name.
Sometime around the end of April or early May is the time to
expect this activity.
Fishing during the Yellowstone's
emergence depends on the spring runoff situation. The yearly
appearance of B. occidentalis and the beginning of spring
runoff frequently coincide. If early May is warm and substantial
snowmelt begins, the fishing is usually in jeopardy. The Yellowstone
can discolor and rise to the point of unfishablility overnight,
ruining some prime early season fishing opportunities. But in
those years when the caddis appear a little early, or when snowmelt
is delayed by cool weather, the fishing can be phenomenal for
both trout and whitefish.
The lower Madison's emergence
can be fished more reliably, because runoff usually does not
begin before the hatch is well underway. On both these rivers,
Brachycentrus emerges over a short time period, often
lasting barely two weeks, but in much more concentrated numbers
than on the Park waters. Both the emergences and the egglaying
flights can be spectacular, with seemingly infinite numbers
of caddis in the air and on the water. It is not uncommon for
huge rafts of spent adults, often inches thick, to build up
in back eddies along shore. The best activity is in the afternoon,
and the fish will feed readily on both emerging pupae and spent
adults. The fish are not difficult to catch, and using a fly
that doesn't even resemble B. occidentalis is often the
best way to compete with a myriad of naturals for a trout's
attention. Downwing attractors like the Royal Trude, which are
easily visible but still possess a general caddis silhouette,
are good choices.
The Henry's Fork at Last Chance,
Idaho, is the only other river in the area where emergences
of B. occidentalis are heavy enough to make it a major
insect. The emergence there lasts from May 25th until approximately
June 25th. This makes it the first caddis of the year to appear,
and aside from Rhithrogena mayflies it is the only other
sizeable insect present at the end of May.
Most of our fishing on the Madison
and Firehole in Yellowstone Park and on the Henry's Fork is
done with adult patterns. Brachycentrus are most active
in the afternoon and evening, and egglaying and emergence often
coincide. Egglaying females sprawl awash on the surface or crawl
underwater. The underwater egglayers usually resurface, then
flop helplessly as they drift downstream. An adult pattern works
well whether the fish are taking egglaying adults or freshly
emerged caddis. We have rarely run into a situation where the
trout feed exclusively on emerging pupae; even when they do,
this early in the season it is still possible to fool them with
adult patterns.
One other species of Brachycentrus
is worth mentioning, and that is americanus (uh-mare-uh-con'-us).
This caddis emerges in August on the Henry's Fork, Yellowstone,
and the Madison below Quake Lake. Brachycentrus americanus
is sparse on the Madison, and we don't consider it a significant
caddis there. They are much more important on the Henry's Fork
and Yellowstone, where tremendous numbers are available to the
trout. Brachycentrus americanus is a lighter gray
than B. occidentalis, but otherwise both species look
similar. Sexual dimorphism is evident in their size too; the
females are a #14, the males a #16. Egglaying is the most important
stage for fishermen, and this can occur anytime during the day
as long as the temperature is fairly cool. Generally in August
this means early morning or evening, though a cloudy afternoon
is ideal also.
On the Henry's Fork we have cast
to fish that were lined up behind protruding rocks and logs,
picking off egglaying B. americanus as they crawled beneath
the surface, laid their eggs, and drifted off with the current.
Large numbers of caddis will use these types of site, and the
steady flow of naturals is a strong inducement to the fish.
Where there are no midstream logs or rocks, the caddis appear
to release their eggs at the surface as they hopscotch along.
Selected emergences:
- Brachycentrus occidentalis
Madison (YNP), Firehole: April 10 - July 4 Henry's Fork:
May 25 - June 25 Madison below Ennis: late April - early May
Yellowstone around Livingston: late April - early May
- Brachycentrus americanus
Henry's Fork: August 10 - August 30 Yellowstone: July
25 - August 30
Hydropsyche
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| The Madison
River below Quake Lake appears at first glance to be a
large, fast-flowing, continuous riffle. For many fishermen
this is a tough sight to reconcile with the classic trout
stream, where shallow riffles separate gentle pools in
a regular sequence. The Madison is definitely intimidating
the first time you fish it, mostly because the eye is
drawn to the river's middle, where heavy, turbulent flows
crash around huge boulders.
Familiarity breeds understanding
though, and as you spend time fishing the Madison you
learn to ignore the middle, concentrating instead on
the slower pockets along the river's edges. These pockets,
which are small and intimate, are where the most fish
are caught. Once this is understood the Madison essentially
becomes a study in small stream fishing, and its charms
are impossible to resist. The Madison flows some forty
miles in the section from Quake Lake to the town of
Ennis, bisecting a valley of sagebrush covered bench
land. Rugged mountains jut from every horizon, and the
highest peaks often hold their snow year-round. On pleasant
summer evenings, which are frequent, the river is a
fly fisherman's paradise.
An angler onstream during
evening hours will discover that the air temperature
drops considerably from its midday high. As the mercury
falls, the strong afternoon winds do likewise. The last
of the fluffy cumulus clouds that build up on most afternoons
sail off over the Gravelly Range, leaving in their wake
a sky so clear and blue and big it could only be Montana.
The Madison turns deep blue too, as the day's last rays
of light reflect from the water. Insects flying over
the surface and the first riseforms are easily spotted
in this evening light.
The trout rise sporadically
at first, their feeding rhythms perfectly mirroring
the insect activity. As darkness sets in the insect
activity intensifies and more trout begin to feed. The
feeding increases steadily until, at dark, trout are
porpoising regularly in every nook, cranny, and hole
available. Choosing just one fish to concentrate on
is necessary but difficult. You're tempted to cover
a different fish if one or two casts go unrewarded,
but this tactic is usually futile. Invariably in these
situations, the browns and rainbows are feeding on emerging
Hydropsyche caddis.
The various species of
Hydropsyche (Hy-dro-sy'-key) are far and away the
most important caddis in this area. They are dominant
elements in the insect communities of many rivers, and
the rises of fish they inspire are Olympian. Of all
the stream insects, only the Pale Morning Dun could
possibly be more significant.
Heavy Hydropsyche
emergences occur on local rivers from the middle of
May until nearly the end of August. This lengthy schedule
results from water temperature variations in the rivers
and from that fact at least four separate species of
Hydropsyche make up this hatch. Hydropsyche
cockerelli (cock-er-ell'-eye) is the first to emerge
each year and is the most abundant. Hydropsyche occidentalis
(ox-uh-den-tay'-lis), H. oslari (os'-lair-eye),
and H. placoda (pla-co'-duh) follow and comprise
the rest of the hatch.
All Hydropsyche
species resemble each other, and they can all be considered
synonymous from an imitation and fishing standpoint.
Adults come in two sizes; #14 and #16 (the females are
usually the larger of the two). Adults have tan wings
and bodies of light brown, golden-yellow, or green.
The differences in body color are apparent only at emergence;
a day or two later the bodies of all species will turn
light brown. The wings always remain tan.
Fish will feed heavily
on Hydropsyche during both emergence and egglaying,
but emergence is the major stage. Emergences occur in
the evening, and can last for several hours. Their intensity
increases as daylight fades, and Hydropsyche
can be found coming off well past dark.
Egglaying usually occurs
sporadically throughout the day, but there are often
peaks in the early morning and early evening. The number
of egglaying caddis you can expect to see, even during
the peaks of their activity, never approaches those
found during the emergences.
The larvae of Hydropsyche
build simple retreats to live in, not true cases like
other caddis. They construct nets to seine particles
of food from the current. Trout no doubt occasionally
feed on larvae accidentally caught in the current, but
we feel they are not important enough to warrant specific
imitations. Evening Hydropsyche fishing generally
follows a predictable pattern. We like to arrive onstream
in early evening in case there are female caddis egglaying.
Egglaying Hydropsyche are easy to see because
they fly low over the water and are fairly large. These
females release their eggs by repeatedly bouncing on
the surface or by flopping and twitching as they drift
on the surface.
During this egglaying
activity, trout will chase the female caddis readily.
Aggressive, splashy riseforms are common in these situations,
regardless of the size of the fish. This feeding is
purely happenstance and opportunistic because the adult
caddis are usually scattered widely. Some fish may see
many caddis, other fish will see none. We prefer to
fish floating adult caddis patterns during this activity
and we limit our casting to rising fish. Doing so avoids
disturbing too much water.
Frequently in the early
evening, male Hydropsyche from earlier emergences
assemble over the water into mating flights. These caddis
flights can completely span a river, and often reach
a height of thirty feet. Many fishermen confuse mating
flights with a caddis emergence or a caddis egglaying
period. They are neither. After flying slowly upriver,
these flights of male Hydropsyche eventually
disperse without ever becoming available to the trout.
Even though no fishing results from the flights, it
is still an impressive sight to witness.
As evening progresses
and the temperature cools, egglaying ceases and emergence
begins. The two stages rarely overlap. As trout begin
taking emerging Hydropsyche pupae, their feeding
rhythm and riseforms change. Dorsal fins and tails often
break the water surface as the fish take the pupae right
beneath the surface. The rises are deliberate and unhurried.
Only the small fish rise aggressively now, at times
rocketing themselves completely into the air in their
efforts to take the pupae.
Though the trout are
feeding primarily on pupae, we do not always fish a
pupal pattern. The Iris caddis or X-caddis, which imitate
an emerging caddis stuck in its shuck, are two of our
favorite patterns to use. These patterns are fished
dry, and they sometimes seem to work better than strict
imitations of the pupae.
Hydropsyche
emergences can last well past dark, and the fish will
continue to feed as long as there are caddis available.
We have found Hydropsyche emerging as late as
11:30 p.m. in July on the Madison River.
On the Firehole River,
it appears that the water temperature influences the
behavior of Hydro-psyche. There are spring and
fall peaks to the emergence; May, June and October are
the best months. Hydropsyche is present but sparse
and scattered during July, August, and September.
Selected emergences:
- Firehole River: May
15 - October 16
- Henry's Fork: May
20 - June 25
- Madison River: June
5 - August 15
- Yellowstone River:
July 10 - August 24
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