From the text:
"Reckon you’re at the stage now where you don’t kill flies and mosquitoes now, I reckon," I said. "Lemme know when you change your mind. Tell you one thing, though, I ain’t gonna sit around and not scratch a redbug."
"Aw dry up," he answered drowsily.
Jem was the one who was getting more like a girl every day, not I.
To Kill a Mockingbird