Flies like to lay eggs on it. And flies prefer to eat moisture-rich liquid food.
Because human food, livestock secretions and excretions, kitchen scraps, and garbage contain abundant organic matter, these are indispensable nutrients for them.
They have a strong attraction to sugar, vinegar, ammonia smell, and fishy smell. Research shows that if female flies are only given water, sugar, and carbohydrates, they can grow but their ovaries cannot develop or lay eggs; only by feeding protein food or various amino acids can they lay eggs normally.
What exactly do they eat on feces: first they rub their feet to clean the food residue stuck in the holes from last time, tasting with their feet, then extend their fleshy pad-like mouthparts, and “spit” digestive fluid from their stomach (of course mixed with the stuff they ate last time), turning the feces into juice, and then suck it up through the mouthparts. Is there nutrition? Although not much, just a little, but for flies it is enough. (food fiber etc.) Another situation is that flies do not eat the feces themselves; they want to have offspring (maggots) inside it. The maggots eat the feces to grow and then become flies.