The toxicity of the essential oils of eighteen Malaysian plants on the 4thinstar larvae of three vector mosquitoes (Anopheles maculatus, Aedes aegypti and Culex quinquejasciatus) was studied. The leaf oil of Litsea elliptica was the most effective, exhibiting LCso of 13.61 f-lg mr! for An. maculatus, 16.01 f-lg
ml for Ae. aegypti and 14.63 f-lg ml for C. quinquejasciatus. The essential
oils from the other species were also toxic with LCso ofl6.58 - 161.12 f-lg ml