Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
This video shows just how blizzard-like the Hexagenia limbata hatch can be. I only wish my digital camera had had respectable video capability back in 2005.
The Namekagon is not known as a Hex hatch river, for good reason: the hatch is extremely rare and localized, and there are often few if any trout where the Hexes are. During this trip I caught nothing and heard no risers, but it was still a memorable night out in the middle of nowhere.