I am going to shed light on the question that has been on everyone's mind for years: Why do female praying mantises eat the heads off of male praying mantises while fucking? I'll tell you why.
Insects have these bundles of nerve tissue throughout their bodies called ganglia. Unlike humans, the insect brain doesn't control things like walking, flying, etc. The "programs" for such behaviors are stores in certain ganglia, and the brain just turns them on or off. So when an insect flies, the brain more or less says "initiate flight program", and the ganglia take care of it; the brain isn't controlling each flap of the wings. In male praying mantises, the program for mating is held in the thoracic ganglion. Once the program is activated, the male will continue mating once the head is removed, and the brain can no longer tell the ganglion to stop the mating process. So basically, by biting the male's head off, the female gets fucked longer, and she gets a free meal.
It should be noted, ladies, that since humans don't work the same the way, biting your man's head off during sex won't stop him from finishing too fast.