What is bug shield?
Herein, do bug shields actually work?
The answer to the question posed in the first sentence, is a resounding yes! Stone and bug deflectors work by altering the actual aerodynamics of your vehicle. While the deflector won't be able to turn everything away from your hood and windshield, it will make sure that most debris won't even touch your vehicle.
Herein, do bug shields stop rocks?
So basically, bug deflectors may prevent damage from small rocks and sand (window pitting) but won't do much (if anything) to prevent impacts that lead to chips or cracks. NOTE: If you're trying to prevent damage to the leading edge of your hood, consider “clear bra” material from 3M.
Bug deflectors are in fact, effective, but we also want to be realistic: they will certainly minimize, but not necessarily totally prevent, bugs from splatting against your windshield. They carry the added benefit of providing some hood protection, and frankly, the models we carry look quite stylish too!