Bumblebees...wasps...anything that is black and yellow, flies, and bites/stings.
I am so terrified of them I won't drive a yellow car because someone once joked the bright color attracts them.
I also won't leave windows open for extended lengths of time in the summer because I am paranoid that they'll find a hole and climb in....in fact last week I went to open my 2nd story window and there were 2 bees on the window sill. I have no clue how they got there (I have detachable screens because my house is an 1892 Victorian so there must have been a gap)...but they are dead in there now...but I am not opening it!!!!!!