Mina

Hi, I'm new here and I'm trying to get some help, I have two roach colonies, one of B. latteralis, one of disciods, neither is doing as well as I would like. They get water crystals and either premium dog or cat food, fish flakes, oatmean, bran, and occasional fruits and veggies. Neither colony has an additional heat source. My question is about housing size. Is it bad for the roaches to be in a tub that is to big and allows them to much room? That and the lack of an additional heat source are the only things I can come up with that might be my problem. Can anyone help?