Sep 19, 2020 - 09:13 AM
It might be a temperature problem in your tray, with heat being trapped at the bottom. Because of their castings (poop), mealworms in a tray can be 20° hotter than the surrounding air killing off your worms in the bottom and mid-layers.
Be sure they are being sifted every 3 to 4 days to keep them cool in the summertime. The bedding should be no more than 2" deep (we keep ours at 1.5") so that heat and moisture can escape through the bedding and not be 'trapped'. The heat, moisture, and castings are the perfect combination for bacteria or fungus to develop on your bedding material causing a bad odor - and attracting ants.
Using wheat bran that is light and airy will help heat and moisture escape while a course, dense bedding like oats can trap heat.