For those who rent, it's worth a shot to ask the owner about installing a screen. I actually had good luck with this once. When I lived in San Telmo in a really old building with only planta baja units, I had one of those slatted windows way up high near the ceiling in my bedroom that I could open and close by pulling a string on a pulley. The window looked out onto this little upstairs patio we had, but it was at the floor level of the patio. Even when the window was closed, there was enough room between the slats for bugs to come in. After I witnessed a cockroach fall through the slats one night, I called the owner and between the roach and the severe mosquito problem we'd been having even though it was winter, he agreed to put in a screen and it was done in two days.
That took care of the roaches and other bugs, but not the mosquitos. At any given point, I could look around and see five or more mosquitos flying around my bedroom. I couldn't figure out where they were coming from, and a lot of them appeared to be newly hatched. I finally came to the conclusion that there must be warm standing water under the pasta shop right next door, perhaps due to a leak near the heat given off by all their equipment, and the newly hatched mosquitos were somehow coming through the pipes in our bathroom to avoid the cold outside, since there were often mosquitos in the bathroom as well. Those suckers were hungry, too. My boyfriend and I would kill as many as we could before going to sleep, but we'd get eaten alive anyway. We called our nightly killing spree la guerra, because inevitably we'd wind up with blood all over the walls. The owner had our pipes checked just in case and they weren't leaking, so I tried all sorts of things, like spraying bug spray down the bathroom and kitchen drains right before everyone went to sleep, but nothing helped. Apparently, other people in the building had the same problem, but no one wanted to confront the pasta shop. I was living there month-to-month, so I moved out. Couldn't take it anymore.
My point is, if anyone happens to find themselves with a severe mosquito problem this winter, not just the odd few survivors flying through a window every now and then, try to figure out where there could be warmth and standing water near your unit and see if you can do anything to get rid of that water.
