I kept several Mantis when I was a kid. I caugt house fly and grass hoppers to feed them. It's fun to watch them catch the fly in mid air. But I had to give up keepting Mantis one day abruptly. I kept two Matis in one cage for a long time and it's fun to watch them face off and box each other from time to time. I didn't know Mantis were canibal. One day I came home from school and saw one Mantis eating the other. The head was gone, he was chewing down his neck, but the prey was still very much alive and breathing. It was so gross to me that I released them and never to keep Mantis again.