Small to medium crickets, butterworms, appropriately sized silkworms, small superworms, flies, terrestrial isopods, cockroach nymphs, etc. Insects should be no bigger than the space between the chameleons eyes, to ensure it can be swallowed easily. The exception to this rule is squishy larva such as silkworms, because, well, they squish! While the chameleons are young, you can feed them as much as they will eat within about 5 minutes, several times a day. That might be as much as 10 bugs each a day. As they get to be adult size, around a year old, you can taper off how much they get.
As they get older, you can also offer collard greens, dandelion leaves, small bits of fruit, shreded carrot, romaine lettuce.