I threw some mealworms in a 5 gallon bucket 15 years ago added some bran every once in a while give them something with some moisture like potatoe peels.

I almost always have more mealworms than I can use. It doesn't take rocket science to grow some,maybe you can get more if you go by the book, but for my personal use this works fine.

Meal worms also grow outside feed mills on the ground in wasted grain.