The pyrethroid insecticide Biflex AquaMax (bifenthrin) was evaluated for its ability to suppress coastal mosquito populations in a controlled suburban backyard study in Mango Hill, Queensland, Australia. The insecticide was applied to perimeter vegetation, fencing in selected backyards, or both, and mosquito populations were monitored weekly from 3 wk before to 8 wk aftertreatment (11 wk total) by using CDC miniature light traps and human bait landing rates. In addition, bioassays were conducted on vegetation and wood surfaces to monitor residual activity. The two most common species in light trap collections were the Ross River Virus vectors Aedes vigilax (Skuse) and Culex annulirostris Skuse. After treatment, Ae. vigilax populations in treated properties were significantly lower (75–90%) compared with untreated properties. In contrast, Cx. annulirotris, Coquillettidia xanthogaster (Edwards) and Mansonia uniformis (Theobald) populations were not impacted by the treatment. Bioassays revealed that the product gave better residual mortality when applied to vegetation (94.6 ± 11.8%) than wooden surfaces (75.9 ± 29.1%) during the 8-wk posttreatment period.