Fruit flies don’t contaminate food in the same way as houseflies, which regurgitate and deposit waste wherever they land. Houseflies are suspected of spreading dysentery, cholera, tuberculosis, and dozens of other diseases. Fruit flies can, however, spread bacteria between different pieces of fruit and vegetables, contaminating fresh fruit with bacteria from rotting fruit. Additionally, they can lay eggs — which will hatch into maggots in as little as 24 hours — in the food you planned to eat. Once fruit flies have claimed a piece of fruit, it’s usually best to let them have it and get it out of your kitchen before the reproduction cycle advances further.