silk worms are one of the better feeders for chams, low in fat and nutritious although you cant really gutload silkies. Wax worms are really high in fat and should only really be given occasionally for a treat. Butter worms are decent to give, high in calcium but a bit fatty make for a good treat. Ive heard hornworms are pretty good too but i cant get them where im from but would like to get some.