We stopped on a small bridge near the exit from Malheur and couldn't believe this huge swarm of Mayflies. Actually, at first we thought they were giant mosquitoes (there are LOTS around here), but when some landed on our windows (there was no way we were going to open them) we could see that they weren't.  It wasn't until we got back to camp and the internet that we figured out what they were, and if they bite (they don't, whew!).