I would recommend starting the different worms in a completely separate bin. Thanks for sharing the picture.For future reference, should you quarantine worms when you get them for a couple weeks, before adding them into your farm? I added them right in, then noticed the die off. I knew it was them because most of my old worms were pupa or beetles when I added them.
Here is my farm, a 10 gallon aquarium. I cut toilet paper rolls in half and stick them in there as little domes, they like to go under them. In the evening the beetles come out and are very active. They seem to like apple pieces better than potato pieces, i've noticed.