I justed received and tried out new extension tubes on bugs at Silver Creek a couple days ago. That essentially allows me to get much closer and as a result get a greater magnification. Mayflies that I saw were: Baetis, Mahogany Duns, Tricos & Callibaetis. Mahoganies and Baetis were the only mayflies I saw in great numbers. October caddis are also fluttering around Silver Creek at the moment.
Female Mahogany Dun
Mahogany Dun Tail