Brush your teeth and take a shower before going out into known mosquito-heavy situations. They definitely like certain blood types, but you can't change that. Things you can change - your bad breath and body odor. Both of those things can attract more mosquitoes. Mosquitoes like carbon dioxide. You can't stop breathing, but what you exhale can be tidied up by brushing your teeth. Swish some Listerine. At the very least it's good dental hygiene. It might seem counterproductive to take a shower before you mow the grass, but it does help keep mosquitoes away if you don't reek like ass while you sweat. Sweat on a clean body is less "aromatic" to mosquitoes than sweat on a dirty body. I've grown up in the deep south and frequently fish in mosquito infested swampy marshlands. These tips work.