Caring for ground beetles?

I recently started catching and housing ground beetles. I'm new to the concept of pet bugs so I'm not entirely sure what I'm doing. I keep them in a medium sized deli cup with 2 inches of dirt at the bottom with moss and rocks. I mist the enclosure every other day. When I first put them in the enclosure there was cat food in there for the pill bugs. They immediately began eating that. I've tried giving them worms, snails and larvae but they didn't eat much. They seem to prefer their soggy cat food. There are pill bugs in the enclosure to clean up droppings and any mold that might grow. I started with 9 and I only have 3 adults left. I recently caught one in the centipede stage on a pitfall trap. They just don't seem to live longer than a few weeks. They get sluggish and they seem to have a hard time walking and they die within a few days afterwards. I know cat food is ok for larvae but I'm not sure about adults. I just put a little paper shelter in the cage. I packed the dirt down enough for them to be able to walk easily but still be able to borough. They mated and laid eggs. Two of. The adults are small and didn't lay eggs. They seem to be thriving. But the last bigger adult lost the use of her back legs and is sluggish. I fear she'll die soon. Is the cage set up correctly? Is there anything else I should feed them? There are holes punched in the lid for ventilation. They are Sidewalk Caribae. Thank you for any feedback!