NSW Arbovirus Surveillance & Vector Monitoring Program
Ochlerotatus alternans

Aedes alternans

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Note that 'Ochlerotatus alternans' prior to 2000, was known as 'Aedes alternans'.

Characteristic Features

Female: A very large mosquito with a 'shaggy' appearance and scaled with mixtures of white, creamy orange, and brown scales, although the general appearance may vary from pale 'orange/white' to dark 'almost-black/white' with different populations; the palps are up to 2/3 length of proboscis which is darker at tip and base but paler in the mid-section; mottling of brown, white and yellowish broad and narrow scales on scutum but indefinable pattern; wing mottled with pale scales and wing fringe with dark and pale segments; legs mottled and with white rings; abdomen with mostly ochreous scaling but mottling or patches of dark and/or pale scales. (Click here for a large photograph of the adult).

Similar Species

Adult females may be confused with the largish Oc. vittiger at times, but these have a striped scutum and shorter palps; Mansonia uniformis are somewhat similar but are much smaller, with shorter palps and a dark wing fringe.

Geographic Distribution

NSW, Vic, SA; (also Qld, NT, WA); coastal and inland environments.

Habits & Habitats

Adult females are vicious biters of humans and other animals, biting by day and night; may disperse several kilometres from larval habitat. The larval stage is predacious on other mosquito larvae.

Vector & Pest Status

A nuisance pest in many areas and noticed because of its size; of no known importance as a disease vector although Ross River virus has been isolated from it on the south coast of NSW.

modified from: Russell, R.C. (1996). A colour photo atlas of mosquitoes of
Southeastern Australia
. Medical Entomology, Westmead Hospital.

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