Silk worms are definately the best, prob followed by horn worms, butterworms are really high in calcium, superworms and wax worms maybe once a month for a treat as they are really fatty. Just buy worms that are sized to your cham, rule of thumb for feeders is nothing bigger than the space between their eyes but I often feed slightly larger with no problems, just keep an eye on him. I have a 5-6 month old female veiledc and she pretty much eats all medium crickets and large worms and is ok with them ( i would give her larger crickets but they r extremely annoying when they chrip)