I think your idea with the black plastic would work fine. You also have the option of keeping the colony going through the winter, but you wouldn't get any larvae to harvest. The larvae you have now will stall their development until spring and they will keep eating if you feed them regularly and insult the unit. This option let's you continue to process waste which will create even more compost. It also will make restarting your colony in the spring easier/quicker.
