Al Caucci and Bob Nastasi popularized this style of dry fly in their book "Hatches". They have remained popular over the years. They float well, are easy to see and the wings are typically more durable than other materials. We like this style for both Sulphurs and BWO types.
The Sulphur mayflies are incredibly important to most Midwestern trout anglers during the months of May and June but can also be found 10 months out of the year on certain tailwaters.