Yes, they are cannibalistic, and will also eat their own droppings, and their young as well. They also feed on dead cockroaches as well but only when there is low supply of food.
The Predators Of Cockroaches Are Spiders, Scorpions, Masked Hunters, Other Assassin Bugs, Centipedes, Rats, Mice, Other Cockroaches, Raccoons, Sugar Gliders, Coatis, Bears, Chimps, Monkeys, Baboons,...