Hello, I am new to the BYC site. I have been raising mealworms for about two years. My sister is the one with chickens, so I raise them for her and for the wild birds during nesting season. I have read most of this thread and have learned a ton. I live in Michigan, so my challenges are trying to keep my worms warm and provide enough moisture during our dry winter. I use wheat bran as my substrate. When I first started, I did try some infant rice cereal and oatmeal that I further ground in a food processor. I found that container took literally twice as long to mature, and the rice cereal got clumped up. I have not had any trouble with mold or mites in my substrate, but I do find that mold develops quickly on potatoes. Carrots dry out quickly in the winter, so I have a hard time finding a reliable vegetable to provide moisture. So, I use a spray bottle and mist the surface of the substrate daily, unless it still feels at all moist. I also have newspaper or part of a brown paper grocery bag laying on the surface, and I spray each layer of those. My containers are open trays and plastic drawers that came from typical Sterilite sets. I keep them in the basement in some lower kitchen cupboards that were left over from a remodel from before we bought this house. I use seedling germination heating pads and strings of xmas lights for warmth.
I wanted to comment on an observation I made recently. I had been keeping my pupae separate from the larvae and beetles, because I have observed the beetles chewing on the heads of the pupae. After reading here that cannabalism should be minimal, I put them back together, and made sure there were apple slices for the beetles to chew on. I noticed an immediate increase in the number of misshapen newly eclosed beetles. So, I took the pupae out again. When they were in their own container with no supplemented moisture, there was 100% perfect eclosures. So, I suspect that there is either cannabalism, or the eclosure process occurs more smoothly under dry conditions. The percentage of malformations, when they occur, is between 10 and 15%, which doesn't seem too bad, except this is at the end of the process. We've finally gotten to the point where we hope to see the population explode, and 1/7 is malformed.
It is time consuming, but I am going to stick with keeping the stages separate.
To increase efficiency, I recommend keeping a folded piece of brown grocery bag on top of the substrate. The mature larvae converge there while they prepare to pupate. So, if you want to collect some to feed the chickens, just pick up the paper and dump them into a container. No sifting or separating sizes. Same goes for taking beetles out of a container to separate them from the eggs they've laid. Put fresh carrots or apple slices or a fresh heel of bread on top and they will swarm to it. Scoop out the pile of beetles and repeat as many times as needed. And, you don't need to get every single beetle out. If you continue to provide moisture, which you should anyway, the few beetles left behind won't eat a significant number of the eggs, and they'll die a natural death soon enough.
Thanks to all who have contributed to this thread. It really is the best source of information out there, since it has experiences from people in different climates and different household situations, with observations over long periods of time as well as common newbie downfalls. Best of luck to all with both their mealworms and all their other critters.