The female praying mantises improves the male's sexual performance by eating his head.
Both the term "Praying" and "Mantis" (Greek: "prophet") refer to the distinctive way these creatures tend to hold up their front legs (as if "in prayer",
Mantises are large carnivorous insects.They normally eat small insects,but they will attack anything that moves.When they mate,the male cautiously creep up on the female,mounts her and copulates.If the female gets a chance,she will eat him,begining by biting his head off,either as the male is approachingor immediately after he mounts or after they seperate.It might seem more sensible for her to wait until copulation is over before she starts to eat him.But the loss of head does not seem to throw the rest of the males's body off its sexual stride. Indeed,since the insect head is the seat of some inhibitory nerve centres,it is possible that the female improves male's sexual performance by eating his head.
From the book The Selfish Gene by Richard Dawkins.