Mayfly Genus Litobrancha

Sorry no photo
While out fishing I came across a big drake spinner. I think it might be Litobrancha Recurvata. 2 tails 17 mm body length, front pair of legs darker than back two, olive abdomen, darker thorax. Collected August 28th, which is relatively late for Litobrancha. Also could be Hexagenia Rigida or Atrocaudata.

Anyone know if Litobrancha or the Late Hexs are present in Southeast Mn?

Caucci and Nastasi's comments and other comments above are correct. They are really hardy and impressive nymphs when they near maturity. Litobrancha nymphs prefer fine silty, mucky habitats in streams. They can be abundant in mucky side channels to the main stream. Their emergence occurs over a 5-day span, with the large majority emerging within a 3-day period. Therefore, large emergences are rarely encountered. When they do occur, they can be very impressive.

From my experience collecting and rearing these critters, they have a 2-year life cycle in PA and MD. They increase tremendously in size in their second year. Emergence occurred in late May into early June about a week before that of green drakes (Ephemera guttulata).