ABSTRACT We investigated the efficacy of a liquid larvicide, Natular 2EC® (spinosad), applied with ultra-low volume sprayer as a residual application during the dry season in southeastern Thailand against 4 medically important species— Aedes aegypti , Ae. albopictus , Anopheles dirus , and An. minimus . We found that this larvicide could be applied as a residual to dry areas known to collect water and potentially still be effective after rains or irrigation, which could increase the flexibility and efficiency of an integrated vector management program targeting these species. This investigation also demonstrated, for the 1st time, efficacy of spinosad against An. minimus and An. dirus .