Does orange juice in a carton attract fruit flies?

My friend and I were given a big plastic carton of Tropicana orange juice at school a few weeks ago, and we didn't know what to do with it so we put it in the locker. A few days ago, there were fruit flies in our hallway. Could the fruit flies be coming from the orange juice in the locker (it's in a carton) and it doesn't smell at all! My other friend also has a tie die tee shirt that's just lying in her locker with a whole bunch of old milk cartons and old lunch boxes. Where do you think the source of fruit flies is coming from?