I have raised many meal worms too. I use oatmeal as the grain. I just buy oat meal and grind it a little in a blender or coffee mill. I also use apple peels for moisture but I would imagine you could use many things. You might try banana peels, orange peels, pears, or whatever. After the beetles reproduce they just die. I throw them in the pond for the fish to eat.

Gotta get back to fishin!