You’re right.
I live on an agricultural farm surrounded by dairy, pig and horse farms.
In the summer, we have your run of the mill flies, horse flies, deer flies, etc. They don’t crawl around on faces.
And this is WINTER for crying out loud!
The only thing I can figure out is he must have a unique odor that draws flies.
That "girlfriend" whom he wrote those ridiculous letter so said he and his room smelled. Maybe that's the first truth we've heard about his past.