Roshan Vijendravarma, of the University of Lausanne, Switzerland, and his colleagues have observed larvae eating older and fatter larvae. The most important part of this observation is that it is a behavior that has been unknown. It suggests that we can still find surprises, even in well studied species.
The fruit fly like other flies, is of the order Diptera, and has mufti-faceted eyes. I have included photos of the well known red eyes at 20 and 40 power on my microscope below. As a side point, if you want to exterminate them, here is a good way to do so: Place two tablespoons of cider vinegar in a dish with one quarter teaspoon of dish soap, any kind and mix well. The cider vinegar will attract them, and the soap traps them from leaving by wetting their bodies making them unable to fly. Here's looking at you!