The house fly may be responsible for spreading diseases, but its body is also quite amazing. It has three pairs of legs - and each leg is divided into five parts, the last part is its foot. Underneath each foot are two small claws and under these claws are little pads that give off a sticky liquid. These sticky pads make it possible for flies to cling to any surface, including the ceiling.
But these sticky pads are also the reason flies are such deadly insects. All the rubbish and sewage on which flies land are full of the germs that cause many deadly diseases, including TB, typhoid fever and dysentery. The germs cling to the sticky pads and when the fly lands on the food we eat, the germs are spread. - bigsiteofamazingfacts.com; open2.net; livescience.com