How can flies walk on the ceiling?

            The feet of a fly are adapted so that they can stick to almost any surface by means of a combination of tiny hooks and sticky pads. A fly’s feet can even grip on shiny surfaces such as glass. When a fly lands on a ceiling, it flies up towards it, and then somersaults into a half-loop so that it finishes in an upside-down position, ready to grasp the ceiling.

Picture credit: google