Addendum to Abigail, the mosquitoes were never a problem to me, but I'm from the Georgia swamps. Nor the sand flies, which we call gnats. Even at the Lamanai ruins in the jungle, the skeeters ain't what I'm used to at home. Never used or needed insect repellant. Most others did. If you get on the back side of the island, away from the breeze, you might find the skeeters a bother. We didn't. They got some biting flies, I'd call em a horsefly, that will put a welt on ya though.
One trick about bugs like mosquitoes, never go out smelling too good. They love soap and perfume smells. The cleaner you are the more they will bite ya. Get ya a 3 day funk going and you won't be bothered any where. Another thing about bugs is don't let them bother you mentally. If you get upset about them you release some kind of pherome that attracts more bugs. This can lead to a frantic circle. Just relaxing and ignoring them can make them go away. Most of you probably don't believe this, but trust me, I live in bug country and the more you swat them the more they bite.