One of my favourite mayflies are the bright, almost nuclear, yellow Heptagenia sulphurea. The yellow sails floating down the silent stream in july are one of the best times to experience as a dry fly junkie. I love the danica and the vulgata because of its majestic size, but that bright yellow mirroring a dark stream is something else. Estetic. iWalkRivers gives you the emerger, dun, spent and an SBS on our spent.
(Notice 1; the color of the spent most likely should be a more rusty shade)
(Notice 2; the emerging sulphurea emerges in its total under the surface and swims to the surface fully emerged. So the question if its needed is totally valid. However, this is our vision of the emerging sulph)