We have noticed that there are piles of the tiny particles of the insulation from one of our garage doors on each side of our door. At first we swept it up and didn't think anything of it. The next day there were piles again! It just keeps happening. Any idea what might be inside of the door eating the insulation or just moving around inside of it to have it pile up on the floor? So strange.
Carpenter ants, they did the same in my insulated (Styrofoam) garage door. They attacked one door but not the second. I stopped them with Sevin dust but it needed a couple months. I just sprinkled it on the floor where the door touched ( because it is "flea powder" it is very low risk to pets.)
Carpenter Ants are making it a new home.