Mosquitoes home in visually to some extent, particularly in the late afternoon, and they seem to like dark colors and movement. But, smell is most important, with the carbon dioxide that you exhale being the primary factor that attracts the pests. Other poorly understood aspects of "personal odor" can have attractant or repellent effects, and probably explain why about 20% of people are considered to be "mosquito magnets" while other folks remain unbothered. Those mosquito magnets are the people you want to stand next to at an outdoor party! No bananas needed.