Yesterday I went across the Mississippi river to a boat landing near Potosi WI. I have been there before and always came back with some macro shots or pictures of the river. As already last year at the same time, there were thousands of black mayflies in the air or hanging at plants. I was really glad to see these wonderful insects since their adult life stage is only 24 hours or less.
It was windy and not very easy to obtain good focus. I got the best results with the camera mounted on a tripod and by waiting for the short moments when the wind calmed down. After checking different sources I believe these are Hexagenia bilineata. I would appreciate if any expert can confirm or correct my analysis.