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. Growing and laying eggs takes a lot of energy. Most insects only mate once, and if the male dies afterwords it doesnt affect its ability to pass on its genes, so the evolved strategy is for the female to eat it and use that energy in making sure the offspring successfully develop and repeat the cycle.