Dragonflies (the huge, teradactyl sized ones we have here) FTMFL.

It's like getting pelted with a huge rock!
And love bug season sucks ass. Come September, it's still hot as hell, and muggy, and then the lovebugs come out. You've literally got to stop every 30-40 miles or so to clean off your visor, cus they're so thick, you can't see!! But even worse than that is that they STINK!!! Oh holy hell, the stench of squashed love bugs is NASTY!!
I believe I hit a bat once (or it hit me) in the shoulder. I saw it coming, and I felt the pain, and I SWORE when we stopped I'd have a huge bloody mark (from the bat, not me) on my (white) jacket, but I didn't. Maybe it lived?