The worst place I've experienced for mosquitos was Sugarloaf Key. During the day, if you swatted you arm, you could easily kill six at a time. At night it got worse. In case Frac thinks he's spent a lot on killing them, there is a bat tower on Sugarloaf that was built to house bats to eat the mosquitos. Depending on which version you believe, the bats left immediately never to return, or never showed in the first place, so it was a total bust.