''Culiseta morsitans'' is a species of

mosquito Mosquitoes, the Culicidae, are a Family (biology), family of small Diptera, flies consisting of 3,600 species. The word ''mosquito'' (formed by ''Musca (fly), mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mos ...

in the family

Culicidae Mosquitoes, the Culicidae, are a Family (biology), family of small Diptera, flies consisting of 3,600 species. The word ''mosquito'' (formed by ''Musca (fly), mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mos ...

, widely distributed in temperate regions of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

. It is

univoltine Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is most often applied to insects, and is particularly in use in sericulture, where silkworm varieties vary in their voltinism. ...

, producing one generation per year, with a life cycle adapted to colder climates. This species is recognized as a secondary

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

for the

Eastern equine encephalitis virus Eastern equine encephalitis (EEE), also called triple E and sleeping sickness, is a viral disease caused mainly by the Eastern equine encephalitis virus (EEEV). Most infections in humans are asymptomatic, but about 5% of the time the infection p ...

(EEEV), primarily affecting

birds Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

but occasionally transmitting the virus to

humans Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...

and

horses The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 milli ...

Description

The

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e of ''Culiseta morsitans'' are identifiable by distinct morphological traits: upper head hairs have 4–6 branches, while lower head hairs are double and notably long. The antenna matches the head's length, is curved, and features a tuft of hairs on its outer quarter extending beyond the tip. The siphon, a respiratory structure, has an index (length-to-width ratio) of 6.0–7.0, with a tuft of 4–5 large hairs near its base within the pecten. Adult mosquitoes are characterized by an entirely dark tarsomere 4 on the hindleg—distinguishing them from related species like '' Culiseta fumipennis''—and

palpi Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicera ...

with scattered pale scales, mostly at the apex. The scutum (dorsal thorax) lacks prominent patterns, and prespiracular setae are present while postspiracular setae are absent.

Life cycle

''Culiseta morsitans'' is univoltine, completing one generation annually. Females lay an average of 109 eggs in rafts on damp soil or leaf litter, a less common trait among mosquitoes, and these eggs overwinter, remaining viable for months under high humidity. Larvae hatch in early spring, typically by mid-April, and develop slowly in cold water habitats. Pupation occurs by late April to early May, with adults emerging in early May and remaining active until September or October. Females are long-lived, often appearing in light trap collections well into summer.

Distribution

''Culiseta morsitans'' has a

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical reg ...

distribution. In North America, it is common in the northern United States, including

New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...

, upper

New York State New York, also called New York State, is a state in the northeastern United States. Bordered by New England to the east, Canada to the north, and Pennsylvania and New Jersey to the south, its territory extends into both the Atlantic Ocean and ...

, and as far south as

Delaware Delaware ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic and South Atlantic states, South Atlantic regions of the United States. It borders Maryland to its south and west, Pennsylvania to its north, New Jersey ...

. It extends across Canada, from

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

, and

Nova Scotia Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...

to the

Yukon Territory Yukon () is a territory of Canada, bordering British Columbia to the south, the Northwest Territories to the east, the Beaufort Sea to the north, and the U.S. state of Alaska to the west. It is Canada’s westernmost territory and the smallest ...

and

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

. In Eurasia, it ranges from Northern and Central Europe to

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

, becoming less frequent in southern regions, where it may be replaced by ''Culiseta litorea''. Its prevalence in colder climates reflects its cold-adapted biology.

Habitat

This species breeds in semi-permanent woodland swamps, shallow

cattail ''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrushStreeter D, Hart-Davies C, Hardcastle A, Cole F, Harper L. 2009. ...

swamps, and root mats in acidic water, often in densely wooded areas with sedge grasses (''Carex'') or mosses. Larvae thrive in fresh or slightly brackish waters rich in detritus, including temporary pools, peat bogs, and undercut root systems. Adults are woodland-dwellers with a limited flight range, typically resting in shaded areas near breeding sites.

Ecology

''Culiseta morsitans'' primarily feeds on birds, contributing to the enzootic cycle of

, with 94.2% of blood meals from avian hosts, 0.8% from mammals, and 5.0% mixed. Larvae feed on organic detritus in water, supporting their role as decomposers in wetland ecosystems. The species is an indicator of wetland health, and its presence is tied to specific environmental conditions like acidic, detritus-rich waters.

Medical importance

Adult females are blood-feeders, predominantly targeting avian hosts but occasionally biting mammals, including humans. ''Culiseta morsitans'' is a secondary vector for

, a severe arbovirus affecting birds, horses, and humans. It has been detected with

in surveillance programs, notably in New York from 1993–2012. Its potential to overwinter

in eggs adds to its epidemiological significance, though this requires further study.

References

External links

Rutgers Center for Vector Biology – Culiseta morsitans

NatureServe Explorer – Culiseta morsitans
{{Taxonbar, from=Q13852319 Culicinae Insects described in 1901