I can hardly kill anything. Not an ant, nor a gnat, not a roach, nor a fly... hmmm... I've just lied - I can exterminate an occasional spider, but only if I've fully exhausted my ability to catch him. This comes from being bitten once. I'll pass on the story, because it's really not a good one. But I survived and the spider likely did too. I am super fond of daddy longlegs. Huntsman they are called, I believe. They have a certain sweetness about them and they are SO calm. They aren't spiders though - they are arachnids, but actually more closely related to scorpions than they are to spiders. If one gets caught in the tub while I'm showering I will do everything I can to save it. They are welcome to reside with me always. Flies are a little trickier. They have some bad habits and I'm not on board with all that ickiness... but still I catch and save them and toss them outside so they can fly back in again.
Afterall, they live here too.