Bug Deflectors

They do work. Run without one and you notice a big difference. Nothing is 100% but I'd guess they knock them down 50-60%. Use some rainX too and it makes your bug cleaning detail easier.

 

I seem to remember the bug deflector keeping light rain from actually hitting the windshield while rolling so i assume that bugs didnt hit so much either.
Note: That was a truck with a flat hood and it was also a long long time ago so who knows what my memory is confusing with what.
Just thought i would give you something to look at till others that have more recent info can answer.

 

I remember them colored plastic things. Everyone would paint their handle on it. Had one on a R model Mack back in the 80s. Kept the bugs off the lower half on my window. I doubt they do anything but screw up the airflow on these slope nose trucks.

Even more ridiculous is those tiny baby wings guys will put on the hood!

 

I was looking at some for a Cascadia but they all required holes to be drilled in the hood and I don't own the truck. The "truck owners" also said it caused some kind of problems with the windshield but didn't go into specifics.

 

One thing to keep in mind, if your truck has a sun visor, and then you add a bug deflector, you've just created a funnel straight to the windshield.

 

You don't see them on new trucks because that 60 dollar piece of plastic or metal will cost you up to $5,000 in extra fuel costs per year. They mess up the air flow that the manufacturer spent millions of dollars to get just right.