For some time I've done experiments with white worms on different mediums, and for me this is both stable and productive method.
This strain does well in room temperature and does not require cooler temperatures to thrive.
Shipped in a breathing bag, with a new sponge and plastic collection net to start your own culture and collecting them for food. Place the sponge to a small container with tight lid. Keep it wet and open the lid often.
Feel free to ask if you have any questions.