Midge / EmergersBiot Emerger
The Biot Emerger is a classic mayfly emerger pattern that utilizes turkey biots to create a segmented, realistic abdomen. This simple yet effective pattern represents the critical emerger stage when mayflies are most vulnerable to feeding trout. The combination of a slim biot abdomen, fuzzy thorax, and antron wingcase creates the perfect silhouette of a mayfly struggling to break through the surface film.
Spring, Summer, Fall
Intermediate
Trout
Dec 2025
Overview
This Charlie Craven pattern from Charlie's Fly Box showcases the effectiveness of turkey biots for creating realistic segmented bodies on small mayfly emergers. The pattern is designed to fish in or just below the surface film where emerging mayflies are most vulnerable. The antron yarn wingcase does double duty, providing both the emerging wing profile and the leg material from the leftover tips. This efficient use of materials keeps the pattern slim and proportional even in the smallest sizes.
Materials
Hook: Tiemco 101, #18-22
Thread: Veevus 14/0, gray
Tail: Spade Hackle Fibers, brown
Abdomen: Turkey Biot, gold dyed
Wingcase: Antron Yarn, olive dun
Thorax: Beaver Dubbing, gray
Legs: Antron Yarn, olive dun (leftover tips from wingcase)
Behavior & Presentation
Natural Behavior: Mayfly nymphs transition from benthic dwelling to surface emergence through vulnerable mid-water ascent. Nymphal shucks begin splitting while insects struggle in the film, creating erratic movements that signal vulnerability.
Where Trout Eat It: Trout sip mayfly emergers in South Platte River tail-outs and slow glides during BWO, PMD, and small mayfly emergences. The segmented biot body positions this pattern in or just below the surface film where fish target insects struggling mid-emergence.
How to Fish It: Fish on 6X-7X tippet as dropper 12-18 inches behind high-floating dry fly indicator. The antron wingcase provides emerger silhouette while the slim biot body rides slightly subsurface, with the supporting dry fly controlling depth positioning.
Best Water: Focus on South Platte tail-outs, seams, and slow glides where emergers concentrate, targeting foam lines and eddy margins in calm water under 3 feet deep.
Strike Type: Watch the indicator for subtle dips or hesitations as fish intercept the trailing dropper below.
Fishing Strategy
Rigging Suggestions: Fish on a 9-foot leader tapering to 6X-7X tippet. Works exceptionally well as a dropper 12-18 inches behind a high-floating dry fly indicator.
Seasonal Timing: Most effective during mayfly hatches. Particularly effective during Blue Winged Olive, Pale Morning Dun, and small mayfly emergences.
Pro Tips: The olive dun antron wingcase provides a subtle emerger silhouette while the beaver dubbing thorax creates the fuzzy profile of a hatching mayfly. Fish this pattern in or just below the surface film.
Entomology
Mayfly nymphs transition from benthic dwelling to surface emergence through a vulnerable mid-water ascent phase where the nymphal shuck begins splitting. During this transitional stage, the insect struggles in the surface film with partially exposed wings while still encumbered by remnants of its exoskeleton, creating erratic movements that signal vulnerability. Trout target emergers preferentially because they represent easy calories combined with predictable concentration during hatch windows.
- Order
- Ephemeroptera
- Common Name
- Mayfly
- Organism Type
- insect
- Life Stage
- emerger