So Bud meets a vampire bat hanging from the roof of the shed. Did it look something like this?
At the end of chapter 4, Bud says that he is "on the lam" just like Public Enemy Number One. He also says that "if J. Edgar Hoover saw me now I'd be in some real serious hot water!" Hoover was the first director of the FBI in the United States. Public Enemy Number One is what the FBI calls their most wanted criminal, the one they want to catch the most. Here's a picture of Mr. Hoover.
By the way, remember Bud saying he was shooting out apologies like John Dillinger shoots out bullets? Well, John Dillinger was Public Enemy Number One in 1934 until Hoover and the FBI caught and killed him.