system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When driving why do some bugs splatter hard onto my windshield, while others seem to get stuck in the wind stream and pass right over it?
gpt
It's a bug weight thing.

A lot of insects are super light. They have small bodies and the lightest of breezes flings them away.

Others have small wings but flap them really fast, or generally don't fly very far with them so they don't have to deal with a lot of wind... and those insects are often heavier. It would take a lot of wind or breeze to move them out of their path.

Now, when you're driving fast, your car creates a "wind" around it. Unless you're going really fast, that deflecting wind will push away almost all small, very light insects and they won't collide with your front glass windshield.

But it does NOT deflect heavy large insects or even heavy small ones with small wings. It just doesn't knock them out of the way fast enough. 

So.... booooosh, and there's that green splat-smear that takes half a tank of wiper fluid to deal with.

(P.S. if your car has a flat front, even tiny and very light insects will whomp into it. The air flow around your can't save 'em all... and so you get a speckled grill as a result.)