How to keep mosquitos out of the house??

Never before coming to Spain have we seen so many mosquitos!! In a single night I got 9 stings! Our apartment is absolutely swarming with them at night even if we completely close all our windows long before sundown. Besides making traps (they don't seem to be working), does anyone have tips to keep them out?? Any sprays that are meant for windowsills or something like that? We don't really want to sleep with chemical sprays on our skin so personal sprays are also not really an option for the night time. Gracias