Check the listing for details. Mayfly - (Pack of 3). Condition: New. Listed at 2.97 USD. A Mayfly fly, also known as a Mayfly imitation or Mayfly pattern, is an artificial fly used in fly fishing to imitate the appearance and behavior of a Mayfly. Mayflies are aquatic insects that undergo a fascinating life cycle, transitioning from nymphs to adults. T he Mayfly fly is designed to mimic the adult stage of the Mayfly, which is when they emerge from the water and take flight. These flies typically feature slender bodies, segmented tails, and delicate wings made from materials like feathers or synthetic fibers. The color and size of the Mayfly fly can vary depending on the specific species being imitated. Anglers use Mayfly flies to target fish species that feed on Mayflies, such as trout and grayling. These flies are often presented on the water's surface or just below it, imitating the natural behavior of adult Mayflies and enticing fish to strike.