I am sure they can, but they should only be for a treat! When I kept reptiles I would refer to those fat little white grubs as "ice cream" for them since that is what they are! Plump and instantly devoured, but full of fat and not really that nutritious unless you have a reptile with a low weight (and only then should they be a supplement to a proper diet). Plus, they can be very expensive!
I do wonder what a chicken would do with an adult tomato hornworm...I may have to get some along with silkworms for treats someday!