Mosquitoes possess eyes, though their visual system operates differently from human vision. While humans perceive a single, high-resolution image, a mosquito’s vision is a mosaic, adapted for survival and host-seeking.
The Structure of Mosquito Eyes
Mosquitoes have two large compound eyes on either side of their head. These compound eyes are not single lenses, unlike human eyes, but are composed of hundreds to thousands of tiny, independent visual units called ommatidia. Each ommatidium acts as its own miniature eye, containing a cornea, lens, and photoreceptor cells. The number of ommatidia can vary between species, generally ranging from around 610 to 900 in adult mosquitoes.
This multi-faceted structure provides mosquitoes with a wide field of view, allowing them to detect movement across a broad range of their surroundings. This results in a lower resolution image compared to human vision, but the compound eye is effective at detecting motion, which is paramount for navigation and finding resources.
How Mosquitoes Use Their Vision
Mosquitoes use vision for navigation, avoiding obstacles, and locating hosts. Their compound eyes are adept at sensing movement and changes in light intensity, allowing them to perceive outlines and shapes rather than detailed images. This ability also aids in navigating their environment. For instance, they prefer dark objects, which often serve as visual proxies for potential hosts.
As a mosquito approaches a target, its visual cues work with other senses. Studies indicate that once female mosquitoes detect carbon dioxide, their visual system becomes more active, prompting them to search for dark objects as they fly upwind toward the CO2 source. This visual detection can occur when the mosquito is within 15 to 50 feet away.
Beyond Vision: Other Sensory Abilities
Vision is one of several sophisticated sensory inputs mosquitoes use to survive and locate blood meals. Mosquitoes integrate multiple cues to find humans. Carbon dioxide (CO2) is a significant attractant, detectable from 10 meters or more. This initial CO2 detection activates flight behavior and initiates host-seeking.
As mosquitoes get closer, they sense other cues, such as body heat and specific chemical odors from human skin. These odors are often produced by skin bacteria and include compounds like lactic acid. This multi-sensory integration means vision, scent, and heat detection work together to guide the mosquito to its target for a blood meal.