I agree with another poster that it's likely aerodynamics. But, it reminded me of an incident when I was a kid. In a minivan, all windows open, highway speeds.

I agree with another poster that it's likely aerodynamics. But, it reminded me of an incident when I was a kid. In a minivan, all windows open, highway speeds. Driver hit a swarm of bees. I've never seen a density of bees like it. Made the windshield opaque for many seconds of wipers and spray, and the number of bees that came through the side windows to be smashed against the back windows and luggage was shocking. I don't know anything about swarming behavior, and it's been years since I thought about that incident. Thanks for the memory!