Thanks man! I was amped to see a golden stonefly adult, I'd never seen one before.
Yes, I have seen a white miller, aka white fly, hatch one time on the Susquehanna. Unfortunately, I was watching a minor league baseball game on Harrisburg's City Island, and not fishing, but still pretty cool. The hatch hadn't even ramped up entirely and yet there were millions of flies around. All the kids were like eww bugs. Meanwhile, I'm trying to contain my urge to geek out about it.
There is a strong white fly hatch on the Potomac main stem, you just gotta get outside the beltway to see it. We are actually in prime time right now for the white fly hatch. They should be popping off about now up on the susquehanna, and if you want to fish them for trout, on the Yellow Breeches. The only difficulty with this hatch is they really start to emerge mostly around 8 pm. Then they get so numerous, and it's so dark, that it is hard to figure out if you've had a strike during your drift!
I'm going to Harper's Ferry tomorrow, so maybe if we stick around long enough I'll have a report and a few snaps on them.