Barr’s Emerger (BWO) – Blue-Winged Olive Emerger

John Barr's BWO Emerger is one of the most effective patterns ever designed for blue-winged olive hatches. It imitates a baetis mayfly in the act of emerging from its nymphal shuck — the exact moment when trout feed most aggressively because the insect is trapped and vulnerable. When fish are rising during a BWO hatch but refusing your dry flies, this is almost always the answer.

BWO hatches happen on nearly every trout stream in America, typically on overcast, drizzly days in spring and fall. They're one of the most reliable hatches of the year, and having the right emerger pattern is what separates the anglers who catch fish during the hatch from the ones who watch.

When to Fish It

Spring and fall during BWO hatches — overcast days from late morning through afternoon are classic conditions. Fish it in the surface film on a dead-drift to rising trout, or as a dropper 6-12 inches below a more visible dry fly. Use fine tippet (5X-6X) and focus on drag-free drifts through pods of rising fish. Size 18 is the standard starting point.

Specs

• Type: Emerger — BWO / Baetis mayfly imitation
• Hook: Fine wire emerger hook
• Weight: Unweighted — designed for surface film presentation
• Best for: Trout — tailwaters, spring creeks, freestone rivers during BWO hatches
• Technique: Dead-drift in surface film, dry-dropper trailer

Why Anglers Stock This Fly

BWO hatches are some of the most consistent and widespread hatches in fly fishing. John Barr designed this emerger specifically to solve the problem of trout refusing dry flies during the hatch — and it works. The pattern has been a staple of serious trout anglers for decades because it consistently catches fish that other patterns can't. Hand-tied with quality materials by tiers with over 30 years of experience.

🎣 Cover the full BWO cycle? Pair this with a Silver Bullet Baetis below the surface and a BWO Dry Fly on top.