Late summer brings a more comfortable existence to those who pursue trout with a fly fishing rod. By September shorter days and cooler nights high up in the Rocky Mountains announce an arrival of fall weather that can be as much as a month earlier than in lower elevations.
Insect hatches on the Henry’s Fork and other notable waters in the Yellowstone region can become somewhat more sporadic and unpredictable during this period of seasonal transition. With consistent potential for opportunity in mind, I am more inclined to rely on a mid-morning spinner fall than trying to time the emergence of several mayfly species that can appear at this time.
Generally, I can arrive on the water at about 9:00 A.M., which is as much as 3 hours later than would be suitable a month earlier in August. Even at this advanced hour a quiet calm can usually be expected to last until at least noon, and this is the condition in which a spinner fall is most likely to occur.
Through much of September and even into early October, early autumn mayflies like Callibaetis and Tricos comprise a significant portion of a trout’s diet, and the spinner stage seems to produce the concentrated numbers of these important insects. They are a significant food source on most area still waters as well as the Henry’s Fork, of which I am especially fond.
Mayfly spinners almost always represent pure dry fly fishing. With the trout looking up exclusively for a meal that arrives from above, precise casting is the name of the game. Because they exist mainly in water with very slow or no perceivable current, Callibaetis and Trico spinners both can induce a feeding pattern marked by travel as trout feed greedily from the surface.
Perfection in timing and accuracy combine with more than a little luck when fishing to a moving target that may never rise in the same place twice. But the satisfaction of having it all come together is something special.
Because mayfly spinners are in a dying or dead condition when they are on the water, an effective fly pattern is often a low floating imitation that can be difficult to see. The CDC Biot Paraspinner does an excellent job of duplicating the spent wings of an expiring spinner while providing welcome visibility with a short, white wing post. And it can also be adapted to any mayfly species.
CDC Biot Paraspinner (Callibaetis)
Hook: TMC 100 BL size 14-18
Tail: Light Pardo Coq-de-Leon
Abdomen: Tannish Gray Goose or Turkey Biot
Thorax: Tannish Gray Dubbing
Wing: Paired White CDC feathers trimmed to 1/3 usual length
Hackle: Sparse turns of Grizzly 2 sizes larger than usual tied parachute style. Trim forward fibers to form a wide “V” over the eye.