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Culiseta impatiens (Walker)
Mosquito
Family: Culicidae
Species account author: Peter Belton.
Extracted from The Mosquitoes of British Columbia (1983)

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Distribution of Culiseta impatiens in British Columbia in British Columbia
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Species Information

A large to very large, dull brown mosquito, with unbanded tarsi; wing length 5-7 mm.

Female

Proboscis and palps dark with a few scattered white scales. Pedicels brown, a few pale scales on darker median surface in some specimens. Scutum with mingled brown and yellowish scales, a pair of yellowish lines extending posteriorly from paired pale spots. Abdominal tergites dark with narrow white basal bands. Tarsi dark. Wing scales dark, more numerous in elongate darker regions at bases of veins Rs, R2+3, M1+2and in area of crossvein r-m.

Larva

Antennae spiculate. Head setae 5 & 6-C 5 or more-branched and almost equal in length (6-C longer than 5-C in incidens and inornata). 40 or more slipper-shaped comb scales in a patch. Siphon 3 x 1, a short pecten near base followed by a row of setae almost reaching apical ΒΌ. 1-S large, many-branched, inserted basally within pecten. Saddle surrounding anal segment. 1-X branched, shorter than saddle.



Glossary of Terms [PDF]

Genus Description


Culiseta, a feminine diminutive of the masculine Culex (ancient Romans did not sex their mosquitoes) was used to separate the species we now know as impatiens from the genus Culex. The name, Theobaldia, was used by several authors until it was found to be invalid having already been used for a genus of Molluscs.

Culiseta females have short palps and a trilobed scutellum and the blunt abdomen resembles that of Anopheles, Culex and Mansonia. Some of our species have patches of dark scales on the wings similar to those of anophelines. Dubious specimens will have to be examined for the presence of prespiracular and absence of postspircular setae.

The single pair of branched setae (1-S) at the base of the siphon characterizes larvae of this genus.

The pupae are difficult to distinguish with certainty from those of other genera. Most collectors will keep them until the adults emerge.

Most Culiseta species in our Province lay their eggs in rafts on water surfaces. Cs. morsitans, however, lays egg rafts on vegetation at the margin of its breeding sites. If the eggs are washed down into the water some may hatch and larvae may overwinter in the benthic debris. If not washed down, the eggs probably overwinter and hatch like those of aedines when flooded in the spring. Most Culiseta species overwinter as fertilized, and probably blood-fed, females and at least some species can produce several generations each year.

Biology

Species Information

This species is found across the Province, most commonly in the Fraser Valley, but nowhere in great numbers. The females emerge from hibernation in early spring, occasionally on warm days when there is still snow on the ground. They oviposit in shaded pools. They are not aggressive biters, and while they attack man on occasion, they usually take blood from other mammals, chiefly cattle.

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
COSEWIC
Unknown/UndeterminedS5No StatusNot Listed



BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Notes

"This species is also widely distributed, is a human biter early in the season. Primarily a woodland species, it is long-lived, with just one generation a year. Its vector capacity and its host preferences later in the year are not known." Belton 2007, with permission).

Reference

Belton, Peter. 2007. British Columbia mosquitoes as vectors of West Nile virus. Peter Belton web site. Simon Fraser University.

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