People have had some success using oatmeal for them, I would think that would work better than using rice flour (or any flour actually), the worms tunnel under the bedding/food, so you don't want anything that will pack very tight and flour has the potential to smother the worms (I would think) while they are tunneling around.
Thank you. They now make gluten free oats. I could try putting a little in there to see if they would like it. I am allergic to normal grains-white flour, wheat, barley, oats & rye. Should the oats be ground up or just put in straight from the bag? I bought gf oats to bake with but I don't care for the taste of oatmeal. But honestly, I rarely bake either;so if my mealworms will like them then the oats wont be wasted.Gf food products can be pretty pricey.