Blue-Winged Olive
Early fall is a temperamental time in Southwest Montana. As night temperatures ease into the 40s, the daytime thermometer might reach 80, but it might also plummet to 30. Snow might collect in the rocky couloirs, or anglers might squeeze 30-proof sunscreen on exposed arms and legs.
Despite all this autumnal inconsistency, one thing is for sure: a delicate insect called Baetis tricaudatus is guaranteed to hatch on several rivers in the Bozeman area. This tiny olive or gray mayfly is better known as the "blue-winged olive," and for good reason. It has a slate gray wing that stands upright off the front third of its drab olive abdomen. Many patterns work for this insect, but a pattern incorporating new materials from Spirit River out of Redmond, OR has made this fly as delicate as necessary without sacrificing its fishy appeal.
To begin, select a light wire dry fly hook such as the Tiemco 100 in sizes 16-20. The finer the wire, the better this pattern will float. Once you’ve placed the hook in your vise, use an 8/0 olive thread to tie in a forked tail in a light dun color. These gray tail fibers can come from a stiff hackle feather, or you can use a synthetic material such as Spirit River's Micro Fibetts. The tail should be the length of the hook shank, which gives the fly added buoyancy. Try to use a minimal amount of thread wraps to avoid a bulky appearance, as the abdomen of the fly should remain thin.
At the tie-in point of the tail, tie in a stripped quill dyed in a drab olive color. These fibers can be very brittle, so it pays to talk to other tiers to find which they like most. Again, I have found that Spirit River's Hackle Quills II are very hollow, yet supple enough to wrap around the hook shank without splintering or breaking. Wrap this quill around the shank, until you reach the halfway point. Tie off the quill and trim it with your thread. You should have created a segmented body that resembles the natural insect's ribbed abdomen.
The next step incorporates an incredible new material that has the uncanny appearance of a Downy dryer sheet, which is dyed into numerous colors; for this pattern you should use dun or gray. Stamped into the sheet are several impressions, which tear easily from the sheet and are pre-formed into a pair of graceful mayfly wings. Fold the pair of wings so the tips match exactly, and place the crease underneath the hook shank so that the curved part of the wing faces toward the tail. Weave your thread in between the two wings in an X pattern to secure the wing to the shank. They should stand upright off the top of the hook, and have a small space in between them. Leave your thread behind the wing for the next step.
Now, using a high-quality dun dry fly hackle, select a feather that matches the size of the hook you’re using. Tie in the fiber with the dull side facing toward the eye of the hook, and with your hackle pliers wrap the feather toward the wings, then in front of the wings two or three more turns. Tie off the feather by weaving your thread through the feathers, and trim it neatly. Use two or three more turns to squash any rogue fibers, and whip finish or use a half-hitch knot to finish the fly. Apply a small amount of head cement, and admire your product.
You are not, however, finished. At this point, a rotary vise comes in handy, but if you have a fixed head on your vise use your hands. Simply remove the fly, turn it over, and with a pair of sharp scissors, trim half the length of the bottom part of the hackle. This step gives the fly a truncated look, but on the river makes the fly sit flush on the stream, which offers the trout a drifting fly with an incredibly realistic appearance.
As early as August, but most likely in mid-September up until the daytime temperatures remain freezing for several days, this trout delicacy called the blue-winged olive will emerge. Cool cloudy days are ideal for this hatch, and it can often run from noon to late afternoon. On sunny days the hatch is much more sporadic and shorter.
The pattern can also be used to imitate several other mayflies, including pale morning duns in June and July, calibaetis on lakes in July and August, and tricos in August and September.
