The X Flies

There I am, sitting at my desk, working away, I pause, take out a ripe plum and open my mouth, all the better to take a bite with. Before I can blink there's a fruit fly staring me in the eye and trying to steal my plum. Fortunately it's too big for him.
Or I'm in the kitchen at home, The knife is poised to cut open a pineapple and whoops, there it is. A fruit fly.
This happens all the time, there are no flies in my home or office until the fruit moment. I can come to only one conclusion.
FLIES LIVE IN ANOTHER DIMENSION and they know how to quickly slip into ours at the first whiff of fruit.
What else could it be and how do we learn this nifty manouvre?