The residual efficacy of λ-cyhalothrin sprayed on foliage was evaluated against various mosquito species in sections of forest in Cairns, Queensland, Australia. Weekly sweep-net collections in treated and untreated areas before and after spraying showed 87–100% reductions in mosquito numbers for the first 9 wk postspray. After that period, reductions fluctuated but remained >71% up to 14 wk posttreatment. Mosquito mortality ranged from 96 to 100% in contact bioassays of treated leaves during the 14 wk study. Our results demonstrate that spraying harborage vegetation with λ-cyhalothrin is an extremely effective strategy for the control of sylvan and peridomestic mosquito species in tropical north Queensland.