Sexual conflict can generate male traits that enhance mating success but lead to injury in females. Pre-copulatory sexual cannibalism—where females eat males without mating—has the potential to select for harmful coercive traits as well, but few examples are known. Here, we show that males of the highly cannibalistic Springbok mantis, Miomantis caffra, wrestle females during pre-mating interactions. We find that most initial contacts between males and females involve a violent struggle whereby each sex tries...