Mosquitoes are common flying insects found in nearly every part of the world, except Antarctica. Over 3,700 distinct types of mosquitoes exist globally. While often considered a nuisance, these insects are also known for their role in transmitting pathogens that can cause illness in both humans and animals.
Why Mosquitoes Bite
Only female mosquitoes engage in biting, a behavior driven by their reproductive needs. Male mosquitoes, along with non-fertilized females, primarily feed on plant nectar and other sugary plant juices for energy. For female mosquitoes, a blood meal is necessary to obtain the proteins and other concentrated nutrients required for the development and maturation of their eggs. Blood provides essential components such as proteins, amino acids, iron, and lipids that are crucial for nourishing the eggs. After consuming blood, a female mosquito seeks a safe location to digest the meal, which then triggers her egg-laying process.
A Diverse Host Palette
Mosquitoes display a wide range of feeding preferences; while some species are highly specialized, many are opportunistic, biting various creatures. Female mosquitoes seek out vertebrates, including mammals, birds, reptiles, and amphibians. They have even been observed feeding on other insects.
Mammals are frequent targets, encompassing not only humans but also a variety of domestic animals such as dogs, cats, horses, and cows. Wild mammals like deer, squirrels, rodents, and even bats also serve as blood sources for different mosquito species. For example, Culiseta melanura primarily feeds on passerine birds but will also bite mammals like horses and humans.
Many mosquito species are ornithophilic, preferring to feed on birds, which can contribute to avian disease transmission. Different bird species, from songbirds to waterfowl, are part of the mosquito’s diet. Some mosquitoes specialize in feeding on reptiles, including snakes, lizards, and turtles. Amphibians such as frogs and salamanders are also hosts for certain mosquito species. For instance, Uranotaenia lowii feeds exclusively on frogs and toads.
How Mosquitoes Find Their Targets
Mosquitoes use sensory mechanisms to locate hosts. They detect a combination of chemical and physical cues emitted by animals. One primary attractant is carbon dioxide (CO2), which hosts exhale with every breath. Mosquitoes possess specialized receptors on their antennae that are highly sensitive to even slight changes in CO2 concentration, allowing them to sense this cue from more than 30 feet away.
Once CO2 is detected, it acts as a homing signal, guiding the mosquito towards the potential blood source. As the mosquito approaches, it begins to sense other cues. Body heat, or infrared radiation emitted by the host’s skin, becomes a significant attractant at closer distances. Mosquitoes use heat sensors to pinpoint landing sites, often targeting warmer areas of exposed skin.
Beyond CO2 and heat, mosquitoes are also drawn to various chemical compounds present in body odors and sweat. These include substances like lactic acid, ammonia, and certain fatty acids such as hexanoic acid. These chemical cues, often in combination, form a complex scent profile that helps mosquitoes identify and home in on potential hosts. The integration of these multiple sensory inputs allows female mosquitoes to efficiently track and find blood meals.