Preliminary Screening: In the preliminary screening 25 essential oils were screened against Cx. quinquefasciatus in order to select effective oils on the basis of larvicidal and knock down effects for further study against Cx. quinquefasciatus, Ae. aegypti and An. stephensi. It was observed that eight oils viz. calamus oil, cinnamon oil, citronella oil, clove oil, eucalyptus oil, lemon oil, mentha oil and orange oil showed 100% larvicidal and knockdown activities. Besides these, geranium, lime, tulsi and palmarosa oils showed more than 92% larvicidal and knockdown activities. Among the 25 oils vetiver oil exhibited the least larvicidal and knockdown effects (Table 1).