Protein Balance
I agree with ferretinmyshoes. Ventilation is important, but if legs are disappearing, cannibalism seems to be the main issue here. Make sure the crickets have plenty of surface area so they're not walking on top of each other (an egg carton is sufficient for 50 crickets). Even with plenty of space, they'll continue to eat body parts if they are protein deficient. There's a delicate balance between providing enough protein for your crickets and avoiding too much protein and fat for your cham. I've had the most success with a multi-veggie mash mixed with coconut oil and nutritional yeast.