I don't like killing things either. Except mosquitos. I LOVE killing mosquitos.
I get fucking distraught whenever I accidentally run over a snail. And let's not talk about frogs jumping around in the lawns I cut during the summer...
But yeah, mosquitos. Love killing them as well. I've found best way is just to grab them with my hand and squash them. They're slow enough to let me do that.
Also wasps. but i have an electric racquet for those.