I think that at home (Western Kentucky) the mosquitos never quit, at least during the summer. Well, they take a siesta when it's the hottest out, but they seem to be active all night long. Where I camp, there's always water nearby, though.
I'm not a mosq-magnet, but my fiance is, so bug nets are a necessity. However, during the winter (we might do more camping when it's cold than not) we don't need netting. I plan to make some net socks so that we only have to carry them when we're going to be using them.