Agreed metz. As a vegetarian, I don't go out of my way to kill bugs, but if a mosquito lands on my arm and starts to suck, you can bet I am not going to ask him politely to go about his buisness and find another snack.
It does get to a point where it is just silly. I think if the nimal doesn't have the cognitive ability to have some kind of spatial awareness that can be processed and has a certain amount of memory capacity there isn't any real point in getting worked up about it.