Breeding fruit flies
I use a very simple method but it works well I use ready break, bran flakes , baby food , a drop of white vinegar.
For 6 pint sizes cups. I grab a large handful of the bran flakes and crush them into fine crumbs. 2 tea spoons of baby food. (the ones you buy in jars and fruit flavour, with no lumps) mix all the ingredients together with water. Add 2 drops of white vinegar, make it so it's sticks to the spoon but it stills drops off.
Place mixture in bottom of cup , add some cotton wool and egg crate , add around 30 flies . cover the top with cloth that has no holes and secure with a elastic band.
Leave for around 10-14 days, you will see maggots in the bottom first and then small brown cocoons in the cotton wool and then lots of flies.