This is something I've been thinking a lot about recently but I'm still not sure what is right. My rule of thumb has been that I'll kill any bug that is infesting my house or causing a problem to my health. Like I would kill termites or bed bugs if I had those, or like a leech or a tick. But recently I've been getting a lot of flies in my apartment and while they are technically "infesting" the place, they're not doing anything to harm me, just annoy me. Is it wrong to kill them?
Also I would like to say that if I encountered any of these bugs out in nature I would leave them alone and not harm them, this is only in the context of a threat to your sanitation or home
Horseflies/gadfly and mosquitos are on my permanent shit-list, no matter where I am and will be terminated with extreme prejudice.. Everything else I just carry out of the house if it can't survive inside properly. Flies seem to make an exit by themselves usually, but if they start to infest the place they will get bonked too.