They follow me around. They don't buzz or sting or anything at all. It is only gnat-size, carries no diseases and is harmless except that it multiplies amazingly fast. Indeed, it can produce generations so rapidly that it is used to study genetics in labs. We have native species in North America, but the really bothersome ones come in as eggs buried in the skins of fresh fruit from tropical countries.
Bananas are a prime carrier.
Once the skin is bright yellow end to end and beginning to show brown spots, bananas can and should go in the fridge lest they go soft and serve as nursery to legions of fruit flies. To deal with your fly population, first try to pay them no mind. They may follow you from room to room in clouds around your head and may dive bomb your cat, but they're just being friendly. Gather your squadron of drosphila and lead them into the bathroom-or well away from any food. Duck quick, zap the cloud of bugs and vacuum or sweep up the remains.