I Hate #19 - Mosquitos
I also really hate that high pitched whine their wings make when they fly. I have an unfortunate reflex that when I hear that whine in my ear, I freak out like a little sissy girl and slap at my head like it's on fire... usually sending my glasses flying and generally ending up looking like a total spaz.
Remember, tip over any containers of standing water you find outside so they can't reproduce in there. Lots of times when you find something with water in it you can see the larva swimming around!