Some 15% of the saltmarsh mosquito, Aedes (Ochlerotatus) vigilax (Skuse) mechanically transmitted the T48 strain of Ross River virus from viraemic donors to uninfected recipient suckling mice. The population tested from near Brisbane was moderately susceptible to infection (ID50=104501 suckling mouse LD50/mosquito) when fed virus diluted in blood on a cotton pledget. Rapid proliferation of the virus in the mosquito allowed transmission from 4 days after ingestion with maximum transmission of 50–57% occurring from 10 days. From assay of Ae vigilax ovaries and of progeny reared from parentally-infected females, preliminary data suggest transovarial transmission as a potential survival method for this virus.