I kill ants if they come into my house, because we have a lot of them round here and have had a full on ant carpet at one point. I don't know what they were doing, but they were all through the downstairs of my house, so, so many of them. It was pretty gross. I was later told that if you see one or two in your house, you have to kill them and not put them out, as they are scouts looking for food. If they find something, they'll go back to the ant hill and get the rest of the troops.
I try to remove anything else, except, if a wasp won't be caught or herded out, I'll swat it. Flies, bees and spiders I wouldn't kill. If I can't remove them, I leave them to it. But I also wouldn't cry if someone else swatted a fly or spider in front of me.
Why is that though? I was veggie as a kid, vegan for a while as an adult. Why don't I mind the idea of insects and spiders being killed 🤔? It's a weird one, for sure.
I wouldn't like the thought of anyone doing it for fun... I would tell off my (afaik NT) dcs if they did it, but that may be quite different. I gave dc1 the riot act for chasing pigeons recently.
I don't think killing insects is a good thing to do by any stretch and it definitely was something I hated at school, when other kids used to catch insects and pull their wings off or whatever for fun 🤢. But, I think that, for some reason, it seems quite different to hurting a mammal or even a bird or reptile.
Also, we had rats running along the back of our houses a while ago and we had to call environmental health, who sent someone round the houses giving advice. Eventually, they discovered a business nearby had a huge compost heap which was completely open and many rats were dining off it and thriving. The business had them all destroyed and again, no, I wasn't exactly heartbroken about that either.