Both species have an extraordinary ability not just to survive cold temperatures but to fly in them. Four years ago, I noted how the 2011/12 brood in Leeds had just come happily through a spell of temperatures as low as minus 12C (10.4F). This year's are having it easy, for now.
The moth uses a sort of natural anti-freeze in its blood to keep active, although its procedures for setting out on an evening flight resemble those of Russian lorry drivers in Siberia who light fires beneath the engine to warm things up. The moth flexes its wing muscles at a gradually increasing rate for up to half an hour. Once this exercise has raised its internal body temperature to 30C (86F), the moth is ready for take-off.
So that's what lies behind its otherwise unremarkable presence on our window pane. A lesson worth recalling when you meet someone who doesn't initially appear to be very interesting. It is true that you never get a second chance to make a first impression. But first impressions can deceive.