The substrate was very moldy!
As you can see the substrate was really moldy when I took this photo, so I decided it was probably time to try and separate the mealworms from the moldy substrate and give them some fresh food. It took ages to sift through all of the moldy oat bran and pick out the larvae – I know at least two of the worms ended up in the bin. What made matters worse was that the spores from the mold were tickling my throat. The mold itself is white, so all of the blue in the above picture is spores!
Anyway, after about an hour I finally managed to remove most of moldy substrate and put the mealworms in a smaller container with some fresh bran. I couldn’t remove all of it so the mixture will probably go moldy again, but as I used less substrate it should be easier to change next time. I also decided to use some pieces of potato peel for moisture instead of the soggy bit of kitchen roll.
I managed to remove most of the moldy substrate
The mealworms are now in a smaller container with less substrate, and a piece of potato peel for moisture