ORANGE HEXEGENIA PATAGONICA
In Patagonia Argentina, where I fish, there's a big nice mayfly, a Hexagenia genus, which produces hatches during spring and summer. (September to March in Southern Hemisphere)
It lives mostly in big glacial euthropic lakes as Nahuel Huapi, Traful, etc. Without doubts is a relative to the Hexagenia limbata, which is very well known in US.