E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Aedes dorsalis (Meigen)
Mosquito
Family: Culicidae
Species account author: Peter Belton.
Extracted from The Mosquitoes of British Columbia (1983)

© Sean McCann  Email the photographer   (Photo ID #66265)

E-Fauna BC Static Map
Distribution of Aedes dorsalis in British Columbia
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Species Information


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Illustration 2


Illustration 3


A medium-sized, fawn-coloured species, yellower on the coast, with indistinct pale basal and apical tarsal bands; wings length 4-4.5 mm.

Female

Palps and base of proboscis speckled with white scales, tip of palp entirely dark. Pedicels brown, white-scaled on median and dorsal surfaces. Scutum with fawn scales, a median stripe of narrow brown scales and, in some specimens, brown posterior half-stripes. The appearance of the median stripe varies across the continent. It is divided in the form found in British Columbia which used to be considered a separate species, curriei. Scales around the margin of the scutum and on the pleuron are whitish in specimens from the interior and yellowish in those on the coast, as they are in coastal California (Bohart & Washino 1978). Hypostigmal and postprocoxal patches many-scaled. Lower mesepimeral setae 2-6. Pleural scales all narrow. Abdominal tergites variable, most specimens have basal white bands widening at the sides and a white median stripe, leaving paired black patches apically on each segment, except I, VII and VIII which are almost entirely white. Femora and tibiae brown, speckled white and dark. Most tarsomeres dark with pale bands apically and basally. Wings with mingled light and dark scales. Dark scales predominate on veins C, R1 and R4+5 and the apices of M1 and M2, the dark scales small and appressed on the last three veins. The wings are almost entirely dark in some specimens and, in this case, their claws will have to be examined to separate them from melanimon. The male genitalia are distinct.

Larva

Head setae 5 and 6-C unbranched. 20-30 ovoid comb scales in a patch, apical spines of equal length. Siphon about 3 x 1, pecten evenly spaced reaching to about mid siphon, 1-S inserted just beyond pecten. Saddle reaching little more than half way around anal segment. Papillae short and blunt, ventral pair shorter than dorsal.



Glossary of Terms [PDF]

Genus Description


Aëdes is the Greek word for disagreeable. Without the dieresis the word means house or building. Although Meigen did not use a dieresis, he translated it as troublesome. Some authorities, therefore, write the generic name Aëdes. Most species of British Columbian mosquitoes belong to this genus. The females all have short palps, usually less than one quarter of the length of the proboscis, and in both sexes the posterior margin of the scutellum is tri-lobed with the setae in three tufts.

Aedes is a large and variable genus and in the field the most reliable character to separate females from other mosquito genera is the pointed abdomen. Males can be identified in the field by their large and separated gonocoxites but if these are not obvious the thorax can be examined for the presence of postspiracular setae which are absent in the males of Culex, Culiseta, and Mansonia. A slide of the terminalia, as well as confirming the genus, can be used to determine the species. (See Wood et at. 1979).

When at the water surface, the larvae of all culicines hang downwards from the hydrophobic tip of the siphon and are thus easily distinguished from anophelines.

Aedes larvae can be distinguished from those of Culex and Culiseta by the position of the siphon seta (1-S). It is never at the base of the siphon in aedines and can be seen with a hand lens if the larva cooperates.

The pupae are hard to identify. It is usually simpler to let them emerge.

Nearly all aedine adults in British Columbia die in late summer or autumn. The eggs are laid singly or in clusters, usually in crevices at the margins of suitable breeding sites. They do not float. Most aedines overwinter as eggs.

Biology

Species Information

This mosquito lives a double life in British Columbia. At the coast it is our principal salt-marsh breeder and I have found a few larvae in rock pools with Ae. togoi and Cs. incidens. In the Fraser delta it is not usually found more than 1 or 2 kilometres inland. It is a more or less continuous breeder in the summer, as successive spring tides flood the marshes. It can, in consequence, be a pest on nearby beaches. Males can be seen at sunset swarming over bushes and tall herbs. At the Tsawwassen salt marsh they seem to favour patches of yellow lupin as swarm markers.

On the interior plateau dorsalis thrives, not only in saline swamps and pools, but also in fresh water such as irrigation seepages. It breeds in open sunny habitats and is typically a mosquito of the grasslands where its flight range may extend for many miles. The females are vicious biters by day or night. WEE virus has been isolated from low percentages of this species in Saskatchewan (McLintock et al.1970).

The species is controlled in the same way as campestris.

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 produces up to two generations a year in saline pools and flooded pastures in the interior of the Province. It is also found in coastal salt marshes around the Georgia Strait and south to CA. It is known to feed on birds occasionally. It is a confirmed vector of other viruses." (Belton 2007). It is a somewhat competent vector of West Nile Virus (Belton 2007).

References

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

Synonyms and Alternate Names

Ochlerotatus dorsalis (Meigen)

Additional Photo Sources

General References


Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 22/11/2019 4:03:03 AM]
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