[nudephil (OP)]

Listener Jeffrey wants to know:

We’ve had a cold and snowy winter, and I’ve had to shovel my driveway every few days. We had a fly in our house, and I was curious if it survived the cold somehow, or recently hatched?

What happens to flies during winter?

[evan_au]

I'm sure if there is food and warmth indoors, flies will multiply all through winter...

[CliffordK]

There are notes on the web that the adult common housefly will typically live for 15 to 30 days in a warm environment. 

Cold below freezing should kill the adults, but low temperatures slightly above freezing may slow down their metabolism, and might extend their lives.

Here are a couple of related topics from the past.

Do flies hibernate?
How can a fly withstand sub-zero temperatures?

[Adam Murphy]

Thanks all for your input. This question has now been answered and you can find it here: https://www.thenakedscientists.com/podcasts/question-week/can-flies-survive-winter