Well.. you may notice that mealworm beetles have a mild smell.. especially if they are agitated (pick one up)

Multiply that smell by 10, make it six times bigger and give it decent sized chompers.. there's a superworm beetle.

I didn't use film canisters.. I found it simpler to put them in the compartments of a simple one level tackle box (or the little craft boxes for jewelry making.. just anything with small individual compartments) ..it was simpler since there was only one lid to open on all the grubs, not a million little canisters.

I dropped a piece of food in each compartment, and slid the box under a cabinet in a cool room. Peek in a few weeks and I saw most of the grubs in a dormant state half curled into a 'C' shape. Few more weeks and they molted into the pupae.