its simple - stop offering him larva and only offer him crickets for awhile. (Assuming this is a healthy adult)
When he is hungry, he will eat the crickets instead of the fatty superworms and mealworms. It will not starve itself, but it will very likely hold out for awhile to see if you give in (as you apparently have before) and give it the larva instead.
Once he returns to eating crickets/roaches, slowly add the silkworms back in periodically. You may want to stop providing mealworms and superworms for a few months, and then only provide them once every few weeks. Make sure you switch up what he gets from meal to meal so that he doesnt get "stuck" on a particular food.