Meal worms need to be contained when they’re placed inside the terrarium. If not, they will quickly ‘escape’ by digging their way into the substrate. There they will remain hidden until they can metamorphose into an inedible beetle. More likely, they will simply die, their decomposing bodies creating a banquet of harmful bacteria. The Exo Terra Worm Dish prevents meal worms from escaping, while allowing them to remain visible to the terrarium inhabitants.