This selection and a couple more early season mayflies are the reason the "Blue Dun" mayfly pattern is such a killing fly. All four mayflies have a fly pattern named after them but, the Blue Dun in different sizes will work for all.
These guys aren't related to each other but they have the same good habit, they hatch midday during the early season. There are two big benefits to this. One; if trout are around they come up to feed and, two; even though early season fishing can be cold midday is usually the most comfortable part of the day. So take advantage of these good habits, sleep in, have a good breakfast, get your gear ready, pack a lunch and hit the water about noon, things should start soon.
The frame to the left will tell you more about some other things your might want to know or bring besides lunch.