since reading the collectible fallout 3 guide I decided to try a tactic mentioned there for fun & enjoyment. a mutant bloatfly (or maybe I'm mistaken about its name) attacked me. I took to a hunting rifle and aimed at its BRAIN (not its head or eyeses) - and disabled it WITHOUT KILLING with one shot. from then on it developed a kind of schizophrenia where it just weant around flying but NOT shooting at me anymore. cool