If your cham chews ( both of mine do) they should have little to no issue with eating hornworms. Mine have ripped them in half actually on a few occasions it was very nasty n messy.. I think an issue with the hornworms is if the cham doesnt grab them by the head the worm can swing around and bite the cham if it's big but it's a rare occurrence. Some people actually crush their jaws prior to feeding them I think. I feed them as is and have no problems and i have been using them on and off since last summer with no incident.