Dart Den

I make three cultures a week, after the first emergence, I have more flies than I need. I was wondering if I can dump most of the flies in a newly started culture, this will be called a "feeder culture".

Is this a good idea ? The feeder culture can house thousands of flies without any problem ?

Yep....you can place them into a single other culture and use it as a feeder culture. I've heard other people do that, yes.