Flies taste their food with their feet.
Why it is true
They have taste receptors on their legs, allowing them to know if something is edible as soon as they land.
Source: Entomology
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.