I have used a corn cob with the mealies. When it was new they crawled all ove it and ate the leftover corn. Now it is an old dry hush and the beetles still crawl on it and I have a feeling that they aly some eggs on it. I keep it in the beetle bin. I did try husks(leaves) as well but they just dried up. The worms liked to hide in them but the just seemed messy!!
For substrate I just mix bran(bought from grocery store) with chicken crumbles,ground flax seed,oatmeal and cornmeal. The wormes seem to do well in this mixture. Figure that I hit all bases!!