NSW Arbovirus Surveillance & Vector Monitoring Program
Ochlerotatus theobaldi
Aedes theobaldi

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

Characteristic Features

Female: Mid-sized mosquitoes of mottled dark appearance; proboscis dark scaled but with extensive pale area on the underside; scutum generally covered with golden and dark narrow scales but with some larger pale towards rear; wings with extensive mottling of broad pale scales; hind legs with femur, tibia and first tarsus mottled, all tarsi banded (although fifth may be all dark); abdominal tergites dark with pale lateral patches and basal bands which may not be complete and there may be some mottling on terminal segments, sternites pale scaled with some dark scales in mottling or apical bands or lateral patches. (Click here for a large photograph of the adult).

Similar Species

Adult females of Oc. theobaldi can be confused with Oc. eidsvoldensis which have the tergal bands produced into a median triangle; other species with mottled proboscis, wings and legs such as Oc. flavifrons (blotch on wing membrane), and Oc. vigilax (fewer pale scales on wing, and scales are narrow like the dark ones not broad) can be readily separated; Oc. normanensis can appear similar but generally has darker proboscis.

Geographic Distribution

NSW (throughout western areas, occasionally on coast), Vic (north/northwest river and western areas), SA (upper Murray), (also Qld particularly west of the Divide) areas.

Habits & Habitats

Adults may become active in spring and be apparent throughout the year in warmer areas providing natural flooding or irrigation promotes an egg hatch; day-biting is usually apparent as the species readily attacks humans and other animals but they will bite also in the evening and at night.

Vector & Pest Status

May be a major pest following extensive rain or flooding in western areas and can disperse for many kilometres when there are major larval populations; the species has been shown to be able to carry Murray Valley encephalitis virus in laboratory studies and Ross River virus has been isolated from collections in the Murray valley, but there is no information as to any role in transmission of human disease.

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

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