Emily Dickinson had a way within her poetry to convey information, and also provide more questions than answers.
In the poem, "I heard a Fly buzz—when I died," there is a great deal of speculation with regard to the presence and meaning of the fly at such a moment. As the speaker explains that all is in place in preparation for her death—personal possessions have been bequeathed, soon-to-be mourners have cried their eyes dry and now only wait, and the subject of the poem prepares for a final breath and the revelation of life after death ("when the king / Be witnessed in his power"), a ordinary fly finds its way into the room.
Some interpreters find this element in the poem horrifying and fearful, suggesting that the fly is symbolic of something terrible, of the physical side of death (decay), or that it is symbolic of Satan present at this moment between life and death.
For me, the fly signifies that life goes on; that the natural world will not note the passing of the woman, and that in her final moments, nothing of import in the world can be of concern to her.
In terms of the haunting in this poem, perhaps it is present as we try to understand how someone dying could possibly write the poem, as if the ending of her life would be recorded, along with her last thoughts, after her death. Wouldn't the speaker be dead to utter the last words of the poem?
With blue, uncertain, stumbling buzz,
Between the light and me;
And then the windows failed, and then
I could not see to see.
At the CUNY/Brooklyn site, possible interpretations are suggested:
For literal-minded readers, a dead narrator speaking about her death presents a problem, perhaps an unsurmountable problem. How can a dead woman be speaking? Less literal readers may face appalling possibilities. If the dead woman can still speak, does this mean that dying is perpetual and continuous? Or is immortality a state of consciousness in an eternal present?
My question looks at the idea of the dead woman still speaking, and in this I find the aspect of "haunting."
"One need not be a Chamber—to be Haunted," also by Emily Dickinson, compares the sense of being haunted by a house or person with the contention that haunting is not solely connected to dwellings or even death. In this poem, the haunting takes place within the individual: past actions, death, guilt cause the person in question to be haunted by these things during life, making their way not through the empty halls of a castle, but the long corridors of the mind.
Dictionary.com defines "haunting" as:
remaining in the consciousness; not quickly forgotten
With this description in mind, we can see how haunting may take place within one's self, perhaps even as the result of the life choices of that self—barring death.
The Brain has Corridors -- surpassing
Material Place --
The speaker says that rather than facing the "Cooler Host" that resides within us, it would be easier to meet just a simple ghost; or...
This madrigal is the form of fear, in assassins, ghouls, and even perhaps a hint of vampires (“through an Abbey gallop,” it speaks of fleeing to a church for protection). The constant theme of fear is well put, for all things of which they speak are beyond your control: assassins, ghosts, vampires, and most importantly, your mind.
In terms of the concept of haunting, it can come from the outside, or we may welcome it within the secret recesses of our minds as it fills us with fear that we create ourselves.