Do you by chance raise your own mealworms? If not, allow a few of the worms to pupate to larval stage. I have had a couple of completely toothless kids who couldn't chew worms or beetles but the larval stage worked great. They are soft bodied in that stage. Not sure why these worked, but I suspect that the little ridges in their body at this stage allowed the hedgehog to move the insect around and manage to actually chew them enough so that they could digest them. Waxworms and other insects would pass right through nearly undigested, but the larval stage mealworms were digested.