Mosquitoes are a group of flies that constitute the family Culicidae, comprising over 3,700 species. They are characterized by a prominent beak-like proboscis, which helps adults feed by drawing up liquids such as nectar and other plant sugars, and in many species, allows females to pierce skin and take a blood meal to support the development of their eggs.
They are holometabolous insects, meaning their life cycle includes four distinct stages: egg, larva, pupa, and adult. While larvae and pupae are aquatic, the adults are aerial and capable of dispersal.
Mosquitoes are an ecologically significant group. While adults contribute to pollination of flowers through nectar-feeding, larvae are an important food source for fish and other aquatic invertebrates. However, many species also act as vectors of human and veterinary pathogens, since female mosquitoes take blood meals and can therefore transmit diseases such as malaria, dengue, chikungunya, yellow fever, Zika fever, West Nile fever, and lymphatic filariasis.
They are typically 0.12 to 0.24 in (3 to 6 mm) long, but the largest mosquitoes in the world, the elephant mosquitoes (Toxorhynchites), are up to 0.71 in (18 mm) long and 0.94 in (24 mm) in wingspan. In contrast, among the smallest mosquitoes are members of the genus Aedes, which have an average wingspan of 0.11 to 0.17 in (2.8 to 4.4 mm).
Being insects, adult mosquitoes have a tripartite body plan, characterized by a head, thorax, and abdomen.
The head comprises a pair of compound eyes on the sides, a pair of sensory antennae, and a highly elongated, forward-pointing proboscis (beak) that helps pierce tissues and suck out fluids.
The proboscis has two main parts: the labium and the fascicle. The labium is the outer, tube-like sheath that surrounds a tightly packed bundle of six thin, needle-like stylets. Together, these six stylets form the fascicle, which penetrates the skin. The fascicle comprises two maxillae (help in cutting), two mandibles (help in sawing and anchoring), one hypopharynx (delivers saliva), and a labrum (forms the canal for sucking fluid).
Many female mosquitoes have a fully developed piercing proboscis with sharp stylets that can penetrate skin and suck blood. However, all males have a reduced, non-piercing proboscis with weakened stylets.
The thoracic region bears three pairs of long, thread-like legs, one pair of functional membranous wings, and a pair of halteres (hindwings modified into balance organs that help stabilize flight).
Like other insects, the thorax has spiracles (openings to the tracheal system) on the sides for gas exchange.
In larval mosquitoes, the head and thorax are fused to form the cephalothoracic region.
The abdominal region comprises 10 segments, though only about 8 are visible in most species. The last two segments are often reduced or modified to form the genitalia, so they may be partly tucked in and not distinctly visible.
This region contains most of the gut and the reproductive organs. The abdominal tip is sex-specific, with females bearing an ovipositor for egg-laying, whereas males have claspers to hold the female during mating.
The word mosquito comes from mosca (‘fly’ in both Spanish and Portuguese) and the suffix –ito (‘little’ in Spanish), so it literally means ‘little fly.’ Similarly, the term Culicidae stems from the Latin word culex, meaning a ‘midge’ or ‘gnat’.
All species of mosquitoes are classified into 2 subfamilies and 112 genera.
The closest relatives of mosquitoes are phantom midges of the family Chaoboridae.
Mosquitoes have a near-global range, found in all continents except Antarctica. Even a few other remote islands, such as Iceland, are free of mosquitoes because they lack standing water or the right temperatures long enough for mosquito eggs and larvae to survive and develop.[1]
Adults typically rest in shady, humid vegetation, though some also shelter indoors or remain close to homes, where they can breed in water-filled containers and easily find human or animal hosts. Mosquitoes can breed anywhere water stands long enough for larvae to develop, including natural habitats such as pond and lake edges, marshes, swamps, and wetlands, as well as vegetated water bodies with floating plants. Many species, especially those in the genus Aedes, also thrive in artificial habitats around homes, including buckets, tires, and gutters.
Most adult mosquitoes, both males and females, derive their nutrition from plant sugars such as nectar, honeydew, and plant juices.[2] However, females of some species, such as the yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus), also take blood meals because blood provides the nutrients required to begin egg development (anautogeny).[3] In contrast, male mosquitoes do not bite and therefore do not feed on blood.
Depending on the species, blood-feeding mosquitoes vary in their host preference. While some mainly bite birds, others feed on mammals (including humans and livestock) or even target amphibians and reptiles such as frogs, lizards, and snakes. For example, Culiseta melanura primarily feeds on the blood of songbirds such as the northern cardinal, American robin, and wood thrush, but when mosquito densities rise, it may also bite mammals, including horses and humans.[4]
Interesting Fact
Research has shown that mosquitoes are most attracted to people with blood group O, whereas they are least attracted to those with blood group A.[5] However, the current evidence is not definitive and is only based on limited studies.
Since larvae live in water, they feed on aquatic algae, microorganisms (such as bacteria and protozoa), and organic detritus. As they develop into pupae, they stop feeding altogether. Feeding begins again after they emerge as adults.
Under ideal conditions, female mosquitoes can live about 6 to 8 weeks. Even without a blood meal, females survive 2 to 3 weeks, since blood is not their primary nutritional source.
However, males have shorter lifespans, usually surviving 10 days or less, simply to mate, after which they typically die.[8]
Around dawn or dusk, male mosquitoes gather in swarms to find mates, releasing pheromones that help attract females into the group. Once a female enters the swarm, mating occurs, and she typically mates only once in her lifetime. In species where egg development requires a blood meal, the mated female then seeks a host and takes a full blood meal. Afterward, she rests for about 2 to 3 days, digests the blood and converts its nutrients into mature eggs. Once the eggs are ready, she lays them.
Female mosquitoes typically lay 100 to 200 eggs in stagnant water during their lifetimes. Usually, in 2 to 3 days, the eggs hatch into larvae, which immediately start to feed. The larvae pass through 4 instars over 4 to 7 days before transforming into a pupa. At the fourth instar, the larva stops feeding and encases itself within a pupal case, transforming into a pupa. Eventually, in 2 to 3 days, the adult emerges from the pupal case at the water surface, with fully developed legs and wings.
These insects are preyed on throughout their life cycle. In water, their eggs, larvae, and pupae are consumed by several aquatic predators, including fish (such as mosquitofish, Gambusia), amphibians (frogs in some habitats), and predatory aquatic insects, such as dragonfly and damselfly nymphs, water beetles, and water bugs.[9]
Once mosquitoes emerge as adults, they are hunted by spiders, adult dragonflies and damselflies, and predatory flies of the families Empididae and Dolichopodidae. They are also opportunistically taken by many birds, such as swallows, swifts, flycatchers, nighthawks, and hummingbirds. Moreover, mosquitoes constitute a significant portion of the diet of many insectivorous bats.[10]
Welcome to AnimalFact - your go-to source for fascinating insights into the amazing world of animals!
