Mealworms, like every other living creature, have a set life cycle. Beetles lay eggs, the eggs hatch to produce larvae (what we call mealworms), larvae pupate, and then new beetles emerge from the pupae. How can I keep my mealworms from pupating before I can feed them to my pet?
The answer is refrigeration, but it’s not as easy as putting them in the refrigerator and leaving them alone. They should be stored in a plastic container with smooth sides (so they can’t crawl out!) with enough wheat bran to cover them. Once a week or so, take them out and allow them to come to room temperature so that they can eat. Add a bit of carrot, potato, or apple for moisture. Leave them out for 12-24 hours, and then put them back into the fridge. Your mealworms should last at least a couple of months if you follow these steps.