The last couple of years I have found mosquitoes in my house in the dead of
winter (like, it's January in western New York, the temperature is hovering
around 5 degrees, and I find the occasional mosquito flying around the
house). We don't generally get mosquitoes in the house in the summer, when
there are relatively lots of them around, and I can't imagine how we can
have them now. They never have blood in them, so I don't think we are being
bitten, but there they are.

Do mosquitoes ever breed indoors? It would seem impossible, since laying
eggs requires blood, and if they were breeding, we would have been bitten.
I'm thinking that they could be using the trap in our shower, which we
rarely use (we have two bathrooms and one is enough for two people), but it
doesn't seem reasonable. They could be hibernating in the attic, I
suppose--it is very warm right next to the ceiling under 12" of insulation.
But it would be hard for them to get into the house from there.

I have never seen this phenomenon before the last couple of years--does this
happen to other people?