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 be the first to grasp hold of the other with their raptorial forelegs. When females win the struggle, they always cannibalise males. However, when males grasp females first, they dramatically increase the chance of mating. We also find striking evidence that males wound females with their fore-tibial claws during struggles, resulting in haemolymph loss and scar tissue formation. Taken together, our results show how males can overcome the threat of cannibalism by coercively wrestling females. We argue that pre-copulatory injury in this species is likely a negative pleiotropic side-effect of selection on claws to capture prey.

Data are tallies of behaviours observed during male-female encounters.