Scientists have identified another factor. The breeze from a fan disperses the human emanations that allow female mosquitoes to zero in on us. (The guys are innocent! Honest! Females need the stolen blood for egg making.)
Humans exhale lots of carbon dioxide — the most widely recognized of the many likely mosquito attractants, including body heat and odors. When a female mosquito senses the invisible gas, she typically flies a zigzag path within the plume to track down its source.