Mealworms can be refrigerated for a long period of time. Store your live mealworms in a shallow container with old-fashioned rolled oats, wheat bran, or meal. Add oats, wheat bran, or meal to Meal Worms at a 2:1 ratio. Mealworms will eat and burrow in the substrate. Remove them from the refrigerator at least once a month to feed on the substrate, and add a carrot slice or potato wedge for moisture while feeding.