A fly has six legs. On each leg there are two little claws that look sort of like a lobster’s claws. Underneath the claws [are] a pair of small weblike fuzzy pads called Pulvilli. These are functional suction pads which the fly presses to the surface to squeeze out the air and create enough suction to hold itself up. Thus with its claws and suction pads, the pests can walk upside down.