Insecticide spray has been commonly practiced for malaria eradication program. Well chosen and accurate dose of insecticide is required to obtain the best result. In this study, a small scaletrial of Actellic 500EC residual spray with dosage ranges of 1.0 ml/m2, 2.0 ml/m2, 4.0 ml/m2 and 5.0 ml/m was applied on wall, shelf and bamboo surfaces. Three malaria vectors e.g. Anopheles aconitus, Aedes aegypti, andCulex quinquefasciatus mosquitoes, 3-4 days old and well fed were used for the experiment using bioassay test kit cone (WHO standard 1975). The result showed that 4.0 ml/m dosages of Actellic 500EC were more effective than the other dosages. The mosquito mortality was 100% in one week for An. aconitus, Ae. aegypti and Cx. quinquefasciatus.