The Mercury Baetis fishes well year-round, but it is especially effective during the height of a blue-winged olive hatch. Baetis nymphs can be identified by their three tails, dark-olive abdomen, and their prominent wing case. The wing case becomes darkened prior to emergence, with an uplifted, swollen appearance, a distinguishing feature that all fly tiers should try to imitate. The Mercury Baetis combines these features, a thin and sparse tail, streamlined abdomen, and black Z-Lon is used for the wing pad and legs. The addition of a sliver-lined glass bead (Mercury Bead) adds a “dash of flash”, which helps mimic the increased luster in and around the thorax area prior to emergence.