Fly Fishing Boatman & Back Swimmers | Aquatic Entomology

In the BC Interior, few things signal the final “feeding frenzy” of the year like the fall Water Boatman flight. Often occurring after the first few frosts of September and October, these “flying oarsmen” hit the water in massive numbers, triggering some of the most exciting and visual trout fishing of the season.

Whether they are migrating between lakes or diving for air, Boatmen and their larger cousins, the Backswimmers, are high-energy meals that trout will chase with reckless abandon.

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The Boatman vs. The Backswimmer

While often grouped together, these two aquatic bugs have distinct differences that anglers should note:

• Water Boatmen (Corixidae): Smaller (up to 12mm), they swim right-side up. They are primarily herbivores and are generally peaceful. They inhabit the shallows and weed beds.
• Backswimmers (Notonectidae): Larger and more aggressive, they swim on their backs. Warning: They are often called “water bees” because they can deliver a painful bite to careless anglers!
• The Silver Bubble: Both insects lack gills. To breathe underwater, they trap a bubble of air against their bodies. This bubble creates a brilliant silvery flash underwater—a trait you must imitate to be successful.

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Behavior: The Flight and The Dive

The Fall “Crash”: During late autumn, Boatmen take to the air to find new waters. They “crash-land” on the surface like rain. Stunned for a moment, they eventually find their bearings and swim frantically for the bottom. Trout wait for this “splashdown” and intercept them before they reach the safety of the weeds.

The Dive Cycle: Because they rely on the air bubble, Boatmen are constantly swimming from the bottom to the surface and back down. This vertical movement makes them vulnerable throughout the entire water column.

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Tactics: The Fast-Sink “Vertical” Struggle

To fish a Boatman effectively, you must mimic the struggle of an insect fighting against the buoyancy of its own air bubble. Our preferred method uses the buoyancy of the fly against the weight of the line.

The Strategy: Use a fast-sinking line paired with a buoyant pattern like our Floater Boater.

• The Sink: Cast and let the line sink. As it drops, it pulls the buoyant Boatman pattern under, perfectly representing the natural dive. Be ready: Trout often hammer the fly on the way down—you better be holding onto your rod!
• The Upward Swim: Once at the bottom, retrieve in quick strips to imitate the swim back to the surface.
• The Pause: Pausing between strips allows the fly to “struggle” upward against the line, mimicking the air bubble’s buoyancy. Most takes occur on this upward retrieve as the trout intercepts the bug heading for air.

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Fly Selection: The One Pattern You Need

Because of the silver air bubble, we focus on a pattern that provides the right silhouette and high buoyancy.

• The Go-To Pattern: The Floater Boater. This pattern is designed to be fished on sinking lines to create the perfect vertical struggle.
• Sizes: #12 to #14 are standard for most BC lakes.
• Visuals: Look for that silvery flash or pearl underbody to represent the trapped oxygen bubble.

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