Lyric discussion by BillyBudd 

I have to admit that I have not read all of the comments for this song, but I did read about half. So I apologize if I am repeating prior interpretations :)

Sufjan is one heck of a lyricist. Love this song and the music. As other posters have commented, it makes sense to me that this song is a reflection of a summer camp trip that Sufjan took with his brother and his friend Franco. In the first stanza, I interpret this to be a young Sufjan, perhaps shortly after the trip writing about his experience. I think a key experience of the trip was the fascination with the predatory wasp. The idea continues to intrigue sufjan that he imagines that it either followed him home or magically appears in his room at night ('thinking outrageously'). I believe the layers of coats and leg warmers are to prevent him from being stung by the wasp- something a very imaginative child would do. It would also explain why he is hiding in his bed (from the wasp). This makes sense when you think how young children continue to cling onto ideas for days and even months after they experience something that really affects them. But as several other people have commented, I believe the wasp is a metaphor as well.

The next stanza recounts the significant experience of the best friend being bit,presumably by the wasp, but is he really bit by the wasp? Sufjan says that he sees the wasp on the length of his arm. Could it be that Sufjan and possibly other friends physically beat up Franco or emotionally through teasing him? The song says that the friend was bit on the shoulder, so why is he washing his face? Is that a metaphor for the shame he is feeling from being teased?
The rest of the song is fairly straightforward. His friend runs away and Sufjan sorely misses him. I think Sufjan extends the wasp metaphor by indicating that he was stung by the loss of his friend. Are the layers of coats and leg warmers to protect against such a loss again- to shield himself from pain- or to prevent himself from acting in such a hurtful manner again?

On other observation. The title refers to a 'predatory' wasp which again makes me think this is about the narrator of the song preying on his friend, unintenionally through teasing. Thinking about it some more, I don't think it has to do with physically abuse, but unintended emotional abuse through teasing. I think the wasp represents the guilt Sufjan feels for possibly causing his friend to run away.

An error occured.