The mosquito's hunting strategy is, say the Californian scientists, "annoyingly robust".
Researchers from the California Institute of Technology began by looking at the insect's sense of smell.
They showed the females - the biting sex - followed plumes rich in carbon dioxide, the gas we breathe out. However, they had no interest in normal air. In situations where carbon dioxide was high, where humans were exhaling, the hungry females were attracted to dark shapes.
Heat was also important, with objects at body temperature of more interest than those at room temperature, the journal Current Biology reports.
Researcher Michael Dickinson said: "Understanding how brains combine information from different senses to make appropriate decisions is one of the central challenges in neuroscience.
"Our experiments suggest female mosquitoes do this in a rather elegant way when searching for food.
"They only pay attention to visual features after they detect an odour that indicates the presence of a host nearby. This helps ensure they don't waste their time investigating false targets like rocks and vegetation."
The research could help in the hunt for better repellents.
The researchers said: "Even if it were possible to hold one's breath indefinitely, another human breathing nearby, or several metres upwind, would create a carbon dioxide plume that could lead mosquitoes close enough to you that they may lock on to your visual signature.
"The strongest defence is therefore to become invisible, or at least visually camouflaged. Even in this case, however, mosquitoes could still locate you by tracking the heat signature of your body."
- Daily Mail
