What decapitated the male Mantis?

Thanks for the insight. Wow, that realization certainly ruined my Sunday, not to

mention the mantis’s. I researched how it could still be sentient. It obviously was able to think, because before I knew what it was, I thought it looked parched and dazed. So I poured a tablespoon of water into a dead leaf ‘vessel’ in front of it, and spilled the same amount onto the concrete next to where it stood, which seeped over to its right feet. It reacted by carefully moving its feet out of the water. It was as though it did need water but couldn’t drink it. Two people on Instagram then told me what it was and one of them speculated it was a post-mating male. It even seemed to have eyes, looked at from the front, but now I know otherwise. I read that mantii can survive decapitated and half-eaten for up to six days. Then I researched invertebrates ability to feel pain, concluded that they do feel pain. I went back to it and it was being eaten by ants. I moved it to another garden location, but a couple ants still clung to it. I asked my husband later if it would have been kinder to have killed it and put it out of its misery. He thought so. By then it was dark, we were walking the dog, and it would have been hard to find. If I ever come across this again, is there a humane way to assist an insect in dying? Thanks again Moira