You can breed them, they are slightly dependant on weather and location though. And you're not gonna want to breed them inside. It needs to be outside unless you have a warehouse that you don't care about getting stinky.
That's why your current location and weather are gonna matter. You can feed the flies food scraps. They are good composters. You're basically going to be making a big compost pile to breed them. The flies will lay their eggs and the larva will eat as they hatch.
It's a lot of setup and trial and error to get right. But once you do it's pretty hands off besides actually getting the larva out.
I tried it once. Wasn't worth it for me.
-Brandon