I used rolled oats and wheat floor. I am probably have to either buy oats from Sam's club or feed store for the wheat bran or ground wheat.
I found on a web site that if buy wheat bran or ground wheat that you have to bake it to kill the grain mites which will live on the beetles and worms then infect the whole colony and then kill the colony.
That means extra work so going to stick with stuff for humans. Unless it cost more than I change.
Grain mites can contaminate your colony from a variety of sources, even the grocery store. Baking helps, but they can still contaminate your colony since they could come in on a bag of chicken feed or dog feed or any grain product and migrate into your colony. The best defense against them is to keep the colony dry, since they can't reproduce at humidities less than 60% or so. FYI, a grain mite infestation won't kill your colony, at least not at first. They're just a big mess to deal with.