Blue-Winged Olive (BWO)
Blue-winged olives (Baetis) are the cool-weather mayfly. Heaviest on overcast spring afternoons (February through May) and again in fall (September through November). Sized smaller than the spring sulphurs but no less productive.
The pattern hierarchy
| Stage | Pattern | Sizes |
|---|---|---|
| Nymph | Pheasant Tail | 18-20 |
| Nymph | RS2 (slate gray) | 20-22 |
| Emerger | Sparkle Dun BWO | 18-22 |
| Dun | Parachute Adams, BWO Para | 18-22 |
The Pheasant Tail and the RS2 cover most subsurface BWO action. Carry both. The Sparkle Dun and Parachute cover the surface hatch.
When to fish what
- Overcast day, before the hatch starts: tight-line a #20 RS2 through riffles. Nymphs are active and migrating.
- Hatch peaks (early afternoon): switch to a Sparkle Dun. Cast to risers; dead-drift through their feeding lane.
- Bright sun, post-hatch: BWOs go quiet. Switch to a midge or wait for evening.
Fall vs spring
Spring BWOs (sizes 18-20) tend to run slightly larger than fall (20-22). Both work the same way. The fall hatch tends to be the more productive one because there are fewer competing food sources.
Tailwater-specific notes
On the Clinch and the SoHo, BWOs hatch in greater numbers than they do on freestone water in the same region. The cold water tail extends the season; you'll see hatches into mid-summer some years.