Bugs in general don’t have any idea whether it is wood or foam, they probably just think it might be a good place to call home. I’ve seen termites use foam as an avenue into a structure and I’ve seen carpenter ants tear up the foam used as insulation. So it didn’t really surprise me when I noticed the damage from carpenter bees. It is extremely difficult to stop them from doing damage to foam, with wood you can paint it and frequently that deters them but not so with these bees and foam.