Natasha's right. Using any kind of repellent frequently is the key. Cactus Juice worked just fine for us at CCV. I kept a bottle of it in our room, one in the gear locker, and one in a tote bag I carried around. It has a fine misting spray that covers well and I used it every time I left the room or got near sand. After 2 weeks I came back with hardly any bites....I'm the token bug magnet!