Mealworm/ beetle substrate?

[SipeCsus]

Hello everyone? Im begining to collect a bunch of beetles from my mealworm container.. Been seperating the pupae as well but i was wondering if any of you guys out their make ur own substrate nd if so what do u guys use?? Been using oatmeal but found mold the other day.. Any help is greatly appreciated!!

 

[sandrachameleon]

This is what I use as the base for both Supers and mealworms
https://www.chameleonforums.com/blogs/sandrachameleon/443-superworm-substrate-gutload-one.html