Flies have a keen sense of smell, and their eating habits are also very diverse. They like incense, sweetness, fishy smell and stink, especially all kinds of rotten organic matter, fermented products, even phlegm, pus and sweat can be eaten. The feeding characteristics of flies are that they spit and pull while eating. The hairs on the whole body and the sticky hairs on the paw pads can carry a large number of pathogen and parasite eggs, which is the main way for flies to spread diseases.