"I heard a fly buzz" was the title we were taught as young tykes in school, although now I find out that these poems have no titles; they are simply numbered. I stuffed 700 bags full of Peoria Visitor Guides and FOLEPI guides today, so I feel as if my brain has been numbed and I will pass out if I do not have dinner. If I don't happen to make any sense, please forgive me.
Basically, what Dickinson's trying to say is that the final moments of this person's life were spent in making a will and then being interrupted by a darn fly. And what in the world is an "...uncertain- stumbling Buzz?" It sounds like the fly was possessed or something.