oh yes maggots can get through places you wouoldn't imagine possibe. At work in the REALLY hot weather 100's, no actually probably 1000's!, of maggots would make their way outo f the bin half way up the drive/car park and gravitate towards the back door of the care home. They would then somehow make it underneath the door and head for the kitchen! Even in the dead of winter when it was freezing outside you could not feel a draught from the door.......so they can definitely make it through seemingly impossible gaps.