I'm wondering if they can be taped over to hide them?

The reason I ask is because I've had someone messing with the gas tank on my car... I filled up yesterday, and now have lost a 1/4 tank of gas. The steel flap in the filler is bent to chit, and I can see tool marks on it!!!

I'm going to town in a couple of hours, and could buy a locking cap, but to be honest I'd rather catch the little rats!!!