Horse flies, I have read, can fly at up to 30 mph. I don't think they're a relative of deer flies. When I was a kid and went camping with the family, the camp's swim area had a raft. We'd all sunbathe on it, but we had to post one lookout for horseflies. After nailing them, we'd toss them into the water as an offering to the smallmouth bass living under the raft. I think the bass liked us, because we never ran out of bass food.

What I call sweat bees are actually yellowjackets, which are a type of wasp. They get very aggressive in the fall and will fly right into a pop can for the sugar. Woe be unto him who tries to drink out of that can!