What can chickens eat that will not effect egg production or consumption (i.e. fly larvae)

[OldmanandtheChi]

I am just starting out and have my chickens in cages (temporarily). A swarm of fly larvae have developed and the few that some of my birds have tried seemed to be appealing to them. My question is what (other than toxins, etc.) are not safe for my birds to eat? Presently I have 12 laying hens, 12 three month old teenagers, and some 4 week old chicks. I have been feeding layer crumbles to my layers and grower crumbles to my others, along with some scratch to all and some grit to the layers. Two of my Barred Rocks seem to be molting, not sure if that is normal. I have read some your members' advice about a variety of diet recommendations. I am anxious to supplement my flock's food with scraps, etc. that will help minimize the need for processed (crumbles) food but augment their vitality and good health.
If I sound like a novice, I am. Any and all advice will be welcome.
I am north of Lafayette, Louisiana (humid and hot).

 

[Chicken Man 16]

If you want good eggs, don't give them to much scratch, and if you give them table scraps, don't give them chocolate or garlic. Like with dogs, chocolate is toxic to chickens. Also, garlic makes their eggs taste weird.