With the weather cooling down and the rain finally subsiding, the fall fly fishing season just around the corner, and I'm sure you all are ready to get back up to those trout streams. The trout will be starting to fatten up for the winter and Brown and Brook trout will be feeding heavily to get ready for the spawn. The question is what are those trout feeding on? Everyone knows about the plentiful spring hatches but most forget about the few insects that hatch into the fall months. One of those insects is the small Trico mayfly, Tricorythodes Stygiatus to be exact. These little olive colored mayflies are one of the few mayflies that can hatch into October. Because of this many people mistake it for the blue winged olive. While BWO's are small as well, they don't get much smaller than a size 18. However, the smaller Trico can be as small as 28. Male Tricos emerge throughout the night and are
not known to be important as duns. They molt into spinners and await
the hatching of their mates. The little olive females emerge in the morning. In the summer this
happens at first light, but it occurs later in the day as the weather
cools down. Female duns can be important to trout, as can the nymphs as
they rise to emerge. The female emergence can be fun to fish, but its
action rarely compares to the spinner fall.
Tricos return as spinners soon after emerging,
sometimes within a few minutes and sometimes a few hours. There is a widespread misconception that
Trico duns molt into spinners in mid-air. This is physically
impossible. Tricos must land to molt, but some of them take off again
before the dun shuck has completely detached from their tails. This give the impression of a mid-air molt The mating
spinners gather in very tight swarms rather than roaming the full width
of the river.
After mating, the males fall spent
and the females fly to shore to rest while squeezing little green balls
of eggs from their abdomens. They return in about half an hour and
fall on the water to drop the eggs. Just remember that when imitating this little mayfly, getting the hook size right can be very important.
Next time you're on the stream you will be able to recognize these little guys (and girls) and will get to enjoy some crazy small dry fly action. Who knows you may join the ranks of the 24 / 24 club.
See you on the trail,