He's immune to the elements, not to nature's other annoyances. Speaking of nature's annoyances: "I seem to have been spared that experience so far, but I appreciate the warning. I'll have to see what Dixon's doing to counter them; unless, of course, he's not met them yet, in which case I shall have to let him know about them.

"What was he explaining? More about how they came to be here? It can't have been particularly good, judging by the expression on your face."