Just got back from 2 weeks in Arillas. We suffered from mozzie bites quite a bit in the first week, but with a bit of care, a plug in, jungle formula, autan and an aftersun spray that included insect repellent we were bite free for the last week. Air con does help and we also used a shower gel that was a strong lemon one. People say that the smell of lemon puts them off.
We did however see a few people who's lower legs were covered in bites. You just need to remember the exposed parts at night. We did and by the end our first week bites had healed up. Enjoy
Gary