No dude, no!
Never wear a hat with dear flies. Let them land in your hair and swat them when they get stuck.
The hat causes them to orbit like a foot or two from your head nonstop.
I once killed over 50 dear flies in a single day hiking in Vermont in July. Holy fuck they were so annoying.
But the hat makes them so much harder to swat. You have to kill them, they wont go away. Once you have 2 or 3 orbiting you will go insane.