On similar lines to Hans' Dame Juliana, but a dry fly.
If you get the wing on a Wullf fly just the tiniest bit too long they will fall "face forward" onto the water. Using a Wally wing reduces the weight and bulk at the head and goes some way to relieving the problem. These were tied for imitating the true mayflies (Ephemerella) so are on the large size. As a general patten it works well in a variety of sizes.

Hook: 8 to 14 long or standard shank (Examples on 12s L/S)
Thread: Tan UTC 70
Wing: Duck flank tied Wally Wing style
Tail: Blue Dun cock hackle fibres.
Body: Hare's ear mixed with a little antron and CdC.
Hackle: Golden Badger.
(As these were for a customer they have the large varnished head customers expect!)