They do not need mealworms nightly. Mealworms are a fairly good source of protein, but they are more of a treat than anything else. They are high in fat, and too much can cause eye problems and obesity.
You can farm them easy enough, we do. Just make sure there is a source of moisture like carrots or potatoes and do not keep them in cornmeal. Aflatoxin is a possible side effect, or if the substrate gets wet. Wood chips or bran are good. We use what they come in from the pet store with some oats added. Aflatoxin can grow in corn substrates, but not other grains or seeds.
They really don't take all that long for new ones to develop. You will see beetles. Mealworms are the larval stage of the beetle. We often feed smaller ones (maybe an inch or 3/4 inch), and supplement periodically with a few from the pet store.