The callibaetis Mayfly emerges the shuck which trails behind the newly emerged dun, this is why they make this fly to imitate the real thing and with very good fishing results. This pattern is a low floating dry fly with an Antron shuck. Very good for trout fishing.

Hook: Standard dry fly hook, e.g. Tmc 900BL
Thread: UNI, size 8/0
Tail: Antron yarn or other synthetic materials
Body: Dry fly dubbing like muskrat
Wing: Deer hair or similar type