Mosquito

The mosquito is a small fly belonging to the family Culicidae, which holds around 3,600 species. Mosquitoes have a slender, segmented body, one pair of scaly wings, three pairs of long, thin legs and a long piercing mouthpart called a proboscis. The body is usually grey or black and typically 3-6 mm long.

The biggest mosquitoes belong to the genus Toxorhynchites, at up to 18 mm long. Mosquitoes in the genus Aedes, which includes the Asian tiger mosquito, are much smaller.

Mosquitoes live in almost every land region except Antarctica. All of them drink nectar, and females of many species also drink blood.

Mosquitoes are true flies, in the order Diptera. The name comes from Spanish and Portuguese and means little fly.

The group diversified during the Cretaceous period. Fossils preserved in amber from Myanmar are about 99 million years old, and Canadian amber holds a mosquito around 79 million years old. Dating based on molecular clocks suggests mosquitoes first arose in the Jurassic.

Mosquitoes are traditionally split into two subfamilies, Anophelinae and Culicinae. Today the Asian tiger mosquito has spread north with a warming climate. By 2023 it was established across southern Europe and as far north as Kent and West London in England.

Most mosquitoes are crepuscular, feeding at dawn or dusk and resting somewhere cool through the heat of the day. The Asian tiger mosquito is known to fly and feed in the daytime.

Females find hosts by smelling carbon dioxide and chemicals in breath and sweat, and also by sight. They are drawn to dark, high-contrast shapes and to red and orange tones. Males feed only on sugary fluids.

The life cycle has four stages: egg, larva, pupa and adult. The first three are largely aquatic, with eggs usually laid in stagnant water such as ponds, puddles or water-filled tree holes. Larvae breathe air through a siphon and feed on algae and microbes. Pupae are called tumblers and do not feed. In hot weather mosquitoes can go from egg to adult in as few as five days.

Males gather in swarms at dawn or dusk, and a female mates only once in her life. After a blood meal she rests for two or three days while her eggs develop.

Adult mosquitoes live from about a week to around a month. Females can live up to three weeks in the wild, depending on temperature, humidity, access to a blood meal and avoiding being killed by their hosts.

Mosquitoes face many natural enemies. Larvae are eaten by dragonfly nymphs, fish, amphibians and ducks. Adults are taken by spiders, dragonflies, swifts, swallows and bats. They can also be parasitised by mites, fungi and single-celled organisms.

Some species spend the winter as adults in a resting state called diapause. In cooler climates, adults may shelter in buildings or hollow trees.

This is general awareness only, not veterinary advice. If you find an injured or unwell wild animal, contact a vet or a wildlife rescue.

What is a mosquito?

A mosquito is a small fly in the family Culicidae. It has one pair of wings and a piercing proboscis. There are thousands of species.

How long do mosquitoes live?

Adults live from about a week to around a month. Females can live up to three weeks in the wild.

Why do mosquitoes bite?

Only females of many species bite. They use the proteins in blood for egg production, and in some species a blood meal is essential for producing eggs. Both sexes otherwise feed on nectar and plant juices.

Do mosquitoes carry diseases?

Many blood-feeding species can pass on pathogens. These include malaria, dengue fever, yellow fever and chikungunya. Nearly 700 million people catch a mosquito-borne illness each year.

Why do mosquito bites itch?

Mosquito saliva passes into the skin during the bite and can cause an itchy rash. Some people react more strongly, as with mosquito bite allergy, which is an excessive reaction to proteins in the saliva.

Why do mosquitoes seem to prefer some people?

They favour people with type O blood, plenty of skin bacteria and high body heat. Attractiveness also has a heritable, genetic component.

The bite is painless because the sharp stylets need only about one thousandth of the force needed to push a needle through skin.

Male mosquitoes beat their wings 450 to 600 times a second.

Anopheles mosquitoes can travel up to 12 km in a night.

Mosquitoes pollinate flowers, including some orchids, and have done so since the Cretaceous.

In the Arctic, swarms can take up to 300 ml of blood a day from each animal in a caribou herd.

The Russian city of Berezniki holds a yearly contest celebrating its mosquitoes.