Rather than breed house flies like that you'd be better off with soldier flies. They dispose of meat scaps and guts faster and have several advantages. One is that soldier flies have no interest in you or anything in your house. In fact they have no mouth parts and don't eat after hatching. They are larger, self harvesting and void their digestive tract before crawling out to hatch so they don't carry any bacteria. If you've raised reptiles you may have bought the pupas under the name "Phonix worms". A soldier fly hatchery is easy to build out of a 5 gallon bucket and a few inexpensive pipe fittings available at any building supply store. You tube has several good clips with instructions for building one.