How do mosquitoes find us?

Three factors seem to guide mosquitoes to us: CO² emissions, our body odor, and the heat we give off. This small insect uses a combination of olfactory, visual, and thermal signals, either simultaneously or independently, to locate its victims. Its modus operandi has been demonstrated in this study from the California Institute of Technology (Caltech).

CO² emissions

The flight of the mosquito (female) is determined by an increase in the level of carbon dioxide in the air (due to our emissions and those of other mammals). Thanks to this precise signal, the mosquito starts hunting for prey to pump the nutrients necessary to lay eggs.

Estrogens

Estrogen secretion may also play a role in the mosquito's "choice" of who to bite. For example, women are more likely to be bitten in the middle of their menstrual cycle and when they are pregnant.

Sweating and body temperature

Heavy sweating and high body temperature are attractive signals to the mosquito. Avoid strenuous physical activity as moisture attracts them, and you can be sure that you are a meal of choice. Conversely, people who do not sweat much seem to be less prone to bites.

And our smells

Particular odors specific to the host or the use of certain medications or supplements that can slightly modify body odor (steroids, amino acids) are a key indicators for the mosquito to know who to bite, as this study and research group in dermato-allergology points out in this book. It seems that we can hardly do anything against the mosquito because the human being secretes about twenty odors able to alert the mosquito's sense of smell.