eli5- Why do insects and arachnids like a praying mantis and spiders kill the one they mate with?

Question

eli5- Why do insects and arachnids like a praying mantis and spiders kill the one they mate with?

In: 499

Answer 1

Food. The ones that killed had mated and now got themselves a small cache of food too…and they did better than the ones who did not kill their mate.

So eating the mate became a thing.