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

I’ll explain this the way my Biology teacher did to me:

The male will do bugger all to raise the children. He’ll just run off and mate with a load of other females, and then run for the hills.

Laying eggs, however, takes a lot of energy.

So to maximise the number of eggs, and thus offspring that survive to reproductive age, the female eats the male, and uses the energy to lay more eggs. And this carries on because females who eat the males have more surviving offspring than those who don’t, so the next generation will have more females that eat the males.