The use of octenol in combination with carbon dioxide (CO₂)-baited encephalitis virus surveillance (EVS) mosquito traps was evaluated under simulated wartime operational conditions during Operation Tandem Thrust (TT01) at the Shoalwater Bay Training area, Queensland, Australia in 2001. A greater number of mosquito species were captured in traps baited with octenol plus CO₂ than those baited with CO₂ or octenol in the saltwater marsh, Freshwater Beach. In the inland environments of Camp Growl and Raspberry Creek, the addition of octenol did not significantly increase the numbers of mosquito species captured. Trap treatment (octenol only, CO₂ only, or octenol plus CO₂) influenced the species captured at Freshwater Beach. More Ochlerotatus vigilax, Mansonia uniformis, and Coquillettidia xanthogaster were captured in traps baited with octenol plus CO₂, and more Anopheles were captured in traps baited with CO₂ only. The most commonly captured (83%) mosquito species in the Shoalwater Bay Training Area during TT01 was the salt marsh breeder and Ross River virus vector, Oc. vigilax.