When the trout are tailing or bulging, nymphs and emerger patterns are most effective. Fish nymphs dead drift lifting them off the bottom at the end of the float. Look for the biggest trout in the best feeding lanes.
Emerger
Fish the same as with nymphs.
Dun
Since other baetis species may be emerging simultaneously, a range of imitations should be carried. At least two body colors (light olive and darker olive) and sizes ranging from #16 to #20.
Catch a natural to determine positively the correct size and color. Vagans hatching in the cool early season have troble getting off the water after emergence. Therefore, dun patterns floated dead drift for long distances is the best imitation.
Spinner
Baetis spinner activity generally made inconsequential by other early season species or by emerging baetis activity.