Mosquitoes are Visual Hunters
Odor is not the only things that cause mosquitoes to be attracted to human beings. The amount of body heat an individual gives off is a great attracter to mosquitoes. When searching for warm-blooded host, mosquitoes instinctively target the hotter specimen for a blood draw.
Studies show, pregnant women, have an average increase of 1.26°F in their body temperature due to the amniotic fluid carried during pregnancy. This is a marker for mosquitoes. If you are outdoors and consume just 12 ounces of beer, the increase in your body temperature can be as much as 1.5 to 2°F. With the consumption of alcohol in the body, metabolizing your drink, your skin markers increase in temperature. If you out of the yard working, sweating, increasing your body temperature by activity, you become a more active target for a mosquito attack.
Instinctively, mosquitoes know where the hot meals by the thermal image you give off. It is a prime indicator that dinner is served. It's almost like the predator movie, you kind of see that thermal outline of the alien, hiding behind bushes or standing on top of the building. You don't really see him but you see that outline, that blurry image of where it is. That is how you look
to a female mosquito searching for a blood meal as she zero's in on a victim.